UTS site search

Professor Francesca Iacopi

Biography

Prof. Francesca Iacopi, PhD

Francesca Iacopi received her MSc in Physics from "La Sapienza" University, Rome, Italy (1996), and her PhD in E.E./Materials Science from the Katholieke Universiteit Leuven, Belgium (2004).

Materials Scientist and Nanoelectronics expert with nearly 20 years’ experience in semiconductor Industry and Academia, she is author of over 120 peer-reviewed publications and holder of 8 granted patents. She achieved international reputation for her contributions to the ITRS roadmap of materials and processes for advanced semiconductor technologies across the area of devices, interconnects and packaging.

Her research emphasis is in the translation of basic scientific advances in nanomaterials and novel device concepts into manufacturable products. In particular, her seminal work on low-k dielectrics for interconnects over the 1999-2009 decade has guided the industrial uptake of porous dielectrics into modern semiconductor chips.

Research Scientist at IMEC (Belgium) over 1999-2009 in the groups of Prof.Karen Maex, Prof.Guido Groeseneken and Prof.Marc Heyns, she then took up a year Guest Professorship at the University of Tokyo (Japan) with Prof.K.Terashima. In 2010-2011 she directed the Chip-Package Interaction strategy for GLOBALFOUNDRIES (Ca, USA), the world’s second -largest semiconductor foundry. At Griffith University she invented a process enable the harnessing of graphene on silicon, with applications in miniaturized technologies, such as bio-compatible sensing and energy storage. At the Faculty of Engineering & IT, University of Technology Sydney since Oct 2016,  she is Professor of Electronics and leads the Integrated Nano Systems (INSys) Lab, focusing on applications for the Internet of Things.

Major awards include: 

- a Gold Graduate Student Award from the Materials Research Society (2003, Boston, USA),

- a Future Fellowship from the Australian Research Council (2012-2016),

- a Global Innovation Award ("Processes enabling low cost graphene/silicon carbide MEMS" , 2014, Washington DC, USA). 

Over 2015-2016, she was one of the 16 founding members of the Advance Queensland Panel of Experts, advisory committee to the Queensland State Government on Science and Innovation. She is a Fellow of the Institution of Engineers Australia and Senior Member of IEEE.

Professional

  • Fellow of the Institution of Engineers Australia (FIEAust)
  • Senior Member of the Institute of Electrical and Electronic Engineers (SMIEEE),
  • Member of the Materials Research Society (MRS), 
  • Australian Institute of Physics (AIP) and the Australian Nanotechnology Network (ANN).
Image of Francesca Iacopi
Professor, School of Electrical and Data Engineering
MA, MSc, PhD
Senior Member, Institute of Electrical and Electronics Engineers
Member, Australian Institute of Physics
Fellow, Institution of Engineers, Australia
 
Phone
+61 2 9514 4410

Research Interests

Smart use and management of energy is rapidly becoming one of the most basic requirements for a sustainable future. A fundamental solution to this is designing devices with ultralow energy consumption, minimising all the parasitic energy losses (electrical, thermal, mechanical) which make devices power-hungry and also less performant. Low energy consumption needs to be complemented with efficient energy storage. Graphene and other 2D materials can enable all of these functionalities.

My group's scope is to design nanodevices with unprecedentedly low energy consumption and dissipation, complemented by solutions for integrated energy storage:

Low-power consumption electronics; low-loss plasmonics; low-damping mechanical systems for highly sensitive molecular recognition; and efficient on-chip energy storage.

Can supervise: Yes
Coordinator, Bachelor of Engineering (Hons), Major in Electronics
  • IoT Components and Technologies 
  • Micro and Nanofabrication
  • Materials Science
  • Semiconductor Technology

Books

Motta, N., Iacopi, F. & Coletti, C. 2017, Growing Graphene on Semiconductors, Psychology Press.
View/Download from: UTS OPUS
This book summarizes the latest achievements in this field, with particular attention to the graphitization of SiC.

Chapters

R.J.O.M. Hoofman, V.H. Nguyen, V. Arnal, M. Broekaart, L.G. Gosset, W.F.A. Besling, M. Fayolle & Iacopi, F. 2007, 'Integration of low-k dielectric films in damascene processes' in Dielectric Films for Advanced Microelectronics, Wiley.
This book is intended for postgraduate level students, PhD students and industrial researchers, to enable them to gain insight into this important area of research.

Conferences

Brock, R.E., Iacopi, F., Iacopi, A., Hold, L. & Dauskardt, R.H. 2014, 'Highly compressed nano-layers in epitaxial silicon carbide membranes for MEMs sensors', 2014 IEEE International Interconnect Technology Conference / Advanced Metallization Conference, IITC/AMC 2014, pp. 241-244.
View/Download from: Publisher's site
Through a novel methodology for evaluating layer-by-layer residual stresses in epitaxial silicon carbide films with resolution down to 10 nm, we indicate the existence of a highly compressed interfacial nano-layer between the films and their silicon substrates. This layer is consistently present underneath all types of silicon carbide films examined herein, regardless of the extent of residual tensile stress measured in the full thickness of the films, which varies from 300 MPa up to 1300 MPa. We link this nano-layer to the carbonisation step of the film growth process and we discuss in detail the implications in terms of fracture behaviour by bulge testing of micro-machined membranes. © 2014 IEEE.
Wang, L., Dimitrijev, S., Walker, G., Han, J., Iacopi, A., Tanner, P., Hold, L., Zhao, Y. & Iacopi, F. 2013, 'Color chart for thin SiC films grown on Si substrates', Materials Science Forum, pp. 279-282.
View/Download from: Publisher's site
In this paper, a color chart based on experimental data was defined for thin SiC films grown on Si substrates. For SiC films thinner than 500 nm, the surface color was observed using an optical microscope with the incident light normally illuminated on the SiC surface. An image of the surface was then taken by a camera attached to the optical microscope and the surface color was defined using RGB code. For SiC films thicker than 500 nm, the colors were defined by observing the films under daylight fluorescent lighting by naked eyes. It was found that the colors of the SiC films varied as the thickness increased. © (2013) Trans Tech Publications, Switzerland.
Yeap, K.B., Iacopi, F., Geisler, H., Hangen, U. & Zschech, E. 2013, 'Nanoindentation for reliability assessment of ULK films and interconnects structures', Microelectronic Engineering, pp. 182-187.
View/Download from: Publisher's site
© 2012 Elsevier B.V. All rights reserved. The structural integrity of interconnect structures containing ultra-low-k (ULK) dielectrics is highly dependent on the mechanical properties of the porous dielectrics, e.g. fracture toughness elastic modulus and adhesion as well. Four-point-bending (FPB) and double-cantilever-beam (DCB) methods for the evaluation of fracture properties require out-of-fab sample preparation and testing. The reliable characterization of interfacial adhesion is important for in-line/at-line process development and control in microelectronics manufacturing. The ability to detect an out-of-spec or defective ULK film at an early process step could potentially save processing and materials cost. Therefore, the development of quick turnaround experimental methodologies for monitoring in-line/at-line mechanical stability of ULK films and ULK-containing interconnects is of great interest for semiconductor industry. This study presents two novel experimental approaches for the evaluation of interface adhesion and mechanical robustness of on-chip interconnects structures based on nanoindentation and nanoscratch, (a) wedge indentation and (b) bump assisted BEOL stability indentation (BABSI) tests, respectively. Wedge indentation tests on ULK films with increasing porosity show a decrease of adhesion values. Correspondingly, BABSI tests show increasing failure rates for Cu/ULK interconnect structures containing mechanically weaker dielectrics.
Hsing, A., Geisler, H., Ryan, V., Cheng, M., MacHani, K., Breuer, D., Lehr, M.U., Paul, J., Iacopi, F. & Dauskardt, R. 2012, 'Microprobing the mechanical effects of varying dielectric porosity in advanced interconnect structures', 2012 IEEE International Interconnect Technology Conference, IITC 2012.
View/Download from: Publisher's site
Chip-package interaction has become a major concern due to increasingly porous low-K dielectrics. During the packaging process, shear stresses are exerted on fragile interconnect structures. We use a microprobe metrology system to experimentally measure how interconnect stacks with different dielectric porosities behave under various shear loading conditions and a wide range of temperatures. © 2012 IEEE.
Hsing, A., Iacopi, F., Lehr, M.U., Geisler, H., Machani, K., Ryan, V., Paul, J., Besser, P. & Dauskardt, R. 2011, 'Mechanical microprobing of Cu pillars and influence of dielectric properties on chip-package interaction', Advanced Metallization Conference (AMC), pp. 52-53.
Heyns, M., Bellenger, F., Brammertz, G., Caymax, M., Cantoro, M., De Gendt, S., De Jaeger, B., Delabie, A., Eneman, G., Groeseneken, G., Hellings, G., Houssa, M., Iacopi, F., Leonelli, D., Lin, D., Magnus, W., Martens, K., Merckling, C., Meuris, M., Mitard, J., Penaud, J., Pourtois, G., Scarrozza, M., Simoen, E., Soree, B., Van Elshocht, S., Vandenberghe, W., Vandooren, A., Vereecke, P., Verhulst, A. & Wang, W.-.E. 2010, 'Shaping the future of nanoelectronics beyond the Si roadmap with new materials and devices', OPTICAL MICROLITHOGRAPHY XXIII.
View/Download from: Publisher's site
Iacopi, F., Choi, J.H., Muneoka, H., Mori, S., Terashima, K., Rice, P.M., Krupp, L. & Dubois, G. 2010, 'Breakthrough reduction of low-k damage with cryoplasma ashing', Advanced Metallization Conference (AMC), pp. 180-181.
We demonstrate that 193nm photoresist material can be etched using an ashing process with plasma gas at cryogenic temperatures at least down to 200K. For equivalent ashing times, the penetration extent of oxidizing plasma species into a 40% porosity OSG dielectric at 200K is three times smaller than at room temperature.
Eslava, S., Urrutia, J., Busawon, A.N., Baklanov, M.R., Iacopi, F., Maex, K., Kirschhock, C.E.A. & Martens, J.A. 2009, 'Effects of silica sources on nanoporous organosilicate films templated with tetraalkylammonium cations', Materials Research Society Symposium Proceedings, pp. 53-58.
Nanoporous organosilicate films have been recently prepared using tetraalkylammonium cations in acid and basic media, outperforming other materials. Resulting films using basic medium were called zeolite-inspired low-k dielectrics. Here we study the dependence of the properties of these films on the used silica sources: methyltrimethoxy silane (MTMS) and tetraethyl orthosilicate (TEOS). A set of experiments varying the MTMS:TEOS ratio were prepared in acid medium and characterized. A textural, physico-chemical, mechanical, and electrical characterization of this series of experiments is presented. © 2009 Materials Research Society.
Gall, M., Grill, A., Iacopi, F., Koike, J. & Usui, T. 2009, 'Materials, Processes, and Reliability for Advanced Interconnects for Micro- and Nanoelectronics - 2009: Preface', Materials Research Society Symposium Proceedings.
Iacopi, F., Rooyackers, R., Loo, R., Vanherle, W., Milenin, A., Arstila, K., Verhulst, A., Takeuchi, S., Bender, H., Caymax, M., Hantschel, T., Vandooren, A., Vereecken, P.M., De Gendt, S. & Heyns, M. 2009, 'Seedless templated growth of hetero-nanostructures for novel microelectronics devices', Materials Research Society Symposium Proceedings, pp. 37-42.
The feasibility of a templated seedless approach for growing segmented p-i-n nanowires -based diodes based on selective epitaxial growth is demonstrated. Such diodes are the basic structure for a Tunnel Field Effe ct Transistor (TFET) device. This approach has the potential for being easily scalable at a full-wafer processing, and there is no theoretical limitation for the control of nanowires growth and properties when scaling down their diameters, as opposed to an unconstrained vapor-liquid-solid growth. Moreover, Si/Si x Ge 1-x hetero-structures are implemented, showing that this can improve the TFET ON current not only due to the lower barrier for the band-to-band source-channel tunneling, but thanks additionally to its lower thermal budget for growth, allowing for better control of the abruptness of the doping profile at the source-channel tunneling interface. © 2009 Materials Research Society.
Iacopi, F., Eichhammer, Y., Massy, C., Vereecken, P.M., Moelans, N., Richard, O., Smeets, D., Blanpain, B., De Gendt, S. & Heyns, M. 2008, 'Indium-assisted growth of Si nanowires: Perspectives on controlled growth for CMOS applications', Materials Research Society Symposium Proceedings, pp. 77-82.
Semiconductor nanowires are attractive nano-building blocks for microelectronics. However, the requirements for their manufacturing and application in the microelectronics industry are very demanding. Beyond compatibility with Si technology, full control on the characteristics of the grown wires (diameter, location, crystallinity, etc.), homogeneity on wafer-scale and reproducibility are essential. In this study we review critically important challenges for a controlled process of In-mediated growth of Si nanowires. First, we stress the importance of surface type for both particle catalysts and growth substrates. Both selection and preparation of such surfaces have large impact on growth, as they influence the initiation and the driving forces for the VLS growth mechanism. Moreover, wire characteristics such as morphology, crystalline quality and growth orientation appear more difficult to control when growing from particles with sizes below 40-50nm. This limitation arises as a result of both fundamental mechanisms and more specific constrains linked to the In-Si system. A few perspectives are given for the achievement of a controlled Si nanowire growth in a Si-technology compatible fashion. © 2008 Materials Research Society.
Iacopi, F., Vereecken, P.M., Schaekers, M., Caymax, M., Moelans, N., Blanpain, B., Detavernier, C., D'Haen, J. & Griffiths, H. 2007, 'Alternative catalysts for si-technology compatible growth of si nanowires', Materials Research Society Symposium Proceedings, pp. 8-13.
The use of Au nanoparticles as catalysts for growth of Si nanowires poses fundamental reliability concerns for applications in Si semiconductor technology. In this work we show that the choice of catalysts can be broadened when the need for catalytic precursor dissociation is eliminated. However, the requirements for selective deposition in a gas phase transport-limited regime become stringent. When competing deposition of amorphous Si can bury the particles faster than the incubation time for VLS growth, no nanowire growth will be initiated. We show that the use of a catalyst such as In, already in a liquid form at the growth temperature, is effective. Therefore, the choice of VLS catalysts among the low melting point metals from the III, IV and V groups is suggested. © 2007 Materials Research Society.
Travaly, Y., Mandeep, B., Carbonell, L., Tokei, Z., Van Olmen, J., Iacopi, F., Van Hove, M., Stucchi, M. & Maex, K. 2007, 'On a more accurate assessment of scaled copper/low-k interconnects performance', IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING, pp. 333-340.
View/Download from: Publisher's site
Travaly, Y., Sinapi, F., Heylen, N., Humbert, A., Delande, M., Caluwaert, R., de Mussy, J.P., Vereecke, G., Baklanov, M.R., Iacopi, F., Hernandez, J.L., Beyer, G., Fischer, P. & IEEE 2007, 'The critical role of the metal/porous low-k interface in post direct CMP defectivity generation and resulting ULK surface and bulk hydrophilisation', Proceedings of the IEEE 2007 International Interconnect Technology Conference, pp. 164-166.
Travaly, Y., Ikeda, A., Tokei, Z., Hendrickx, D., Carbonell, L., Struyf, H., Li, Y.L., Verheyden, G., Hoofman, R., Kemeling, N., Fukazawa, A., Matsuki, N., Iacopi, F., Sprey, H., Beyer, G. & Van Hove, M. 2006, 'Improvement of the electrical performance of Cu/Aurora (R) ULK interconnects using an advanced BEOL integration scheme', Advanced Metallization Conference 2005 (AMC 2005), pp. 81-87.
Ikeda, A., Travaly, Y., Humbert, A., Hoofman, R.J.O.M., Li, Y.-.L., Tokei, Z., Iacopi, F., Michelon, J., Bruynseraede, C., Willegems, M., Hendrickx, D., Van Aelst, J., Struyf, H., Versluijs, J., Heylen, N., Carbonell, L., Richard, O., Bender, H., Kaiser, M., Weemaes, R.G.R., Verheyden, G., Kemeling, N., Fukazawa, A., Matsuki, N., Sprey, H., Ciofi, I., Beyer, G. & Van Hove, M. 2006, 'Low-k properties and integration processes enabling reliable interconnect scaling to the 32 nm technology node', Proceedings of the IEEE 2006 International Interconnect Technology Conference, pp. 42-44.
Iacopi, F., Travaly, Y. & Beyer, G. 2006, 'Organosilicate glasses for interconnects: What makes the difference in a sea of low-k dielectrics?', Proceedings - Electrochemical Society, pp. 8-16.
The matrix materials of OSG dielectrics can be extremely different in terms of short- and medium- range bonding and spatial arrangement. This results in a large variation of dielectric film thermo-mechanical properties even for films with comparable porosity. An enhanced degree of cross-linking of the matrix material and the predominance of strong, small angle silica bonds with respect to the large angle ones improve considerably both mechanical stability and thermal conductivity of organosilicate films. In most cases there is room for significant improvement of the films thermal and mechanical properties without causing significant densification by rearranging the matrix/skeleton material structure. The combined use of Nuclear Magnetic Resonance (NMR) and Fourier Transform Infra Red Spectroscopy (FTIR) is key to the interpretation of the different glass structures.
Molina-Aldareguia, J.M., Elizalde, M.R., Ocaña, I., Gil-Sevillano, J., Martínez-Esnaola, J.M., Iacopi, F., Travaly, Y. & Van Hove, M. 2006, 'Use of nanoindentation to characterise the plasma damage region in low-k dielectric films', American Society of Mechanical Engineers, Applied Mechanics Division, AMD.
View/Download from: Publisher's site
The thermo-mechanical robustness of interconnect structures is a key reliability concern for integrated circuits. The introduction of new low dielectric constant (low-k) materials with deteriorated mechanical strength (i.e., Young Modulus decreases exponentially with film porosity, which is needed to lower the k value of the dielectric materials) to meet the RC delay goals increase the risk of mechanical adhesive and/or cohesive failure of the device during packaging or even in service. Therefore, the mechanical properties of low-k dielectrics must be studied in detail. This is made very challenging by the fact that they have submicron thickness and that they often display a graded structure due to the damage introduced by exposure to different plasmas during processing. In this context, we demonstrate that nanoindentation is very well suited to study this type of materials. We will show how conventional depth sensing nanoindentation is of limited value to characterise the extent of the plasma induced damage because this extents just a few tens of nanometres and the graded structure can not be sampled with enough depth resolution. However, nanoindentation in modulus mapping mode can achieve enough depth resolution to characterise such nanoscale graded structures. In this technique, the electrostatic force acting on the indenter tip is sinusoidally modulated, while contact mode imaging at a very small force is performed. The dynamical response is then analyzed to extract the local indentation modulus of the sample at each pixel. By using this technique, we have depth profiled the mechanical properties of the plasma induced damage region of OSG films exposed to different plasmas, by acquiring modulus maps as a function of thickness removed in wear experiments. The results correlate well with the density depth profiles derived from X-Ray Reflectivity measurements. Copyright © 2006 by ASME.
Iacopi, F., Waldfried, C., Houthoofd, K., Guyer, E.P., Gage, D.M., Carlotti, G., Travaly, Y., Abell, T., Escorcia, O., Beyer, G., Berry, I., Dauskardt, R.H. & Maex, K. 2006, 'UV-assisted curing: an effective technique for toughening low-k organosilicate films', Advanced Metallization Conference 2005 (AMC 2005), pp. 247-254.
Eslava-Fernandez, S., Baklanov, M.R., Iacopi, F., Brongersma, S.H., Kirschhock, C.E.A. & Maex, K. 2006, 'Zeolite low-k film properties dependence on nanocrystal size', Materials, Technology and Reliability of Low-k Dielectrics and Copper Interconnects, pp. 421-426.
Brongersma, S.H., Iacopi, F., Vanstreels, K., Tökei, Z., Bruynseraede, C., Demuynck, S. & D'Haen, J. 2006, 'Stress in next generation interconnects', AIP Conference Proceedings, pp. 157-163.
View/Download from: Publisher's site
Stress is becoming an increasingly critical parameter for all steps in back-end-of-line integration. As the k-value of dielectric spacers decreases their mechanical integrity scales accordingly, making the interconnect stack increasingly sensitive to barrier and copper stresses. These stresses need to be studied not only for as-deposited layers, but also during thermal processing. Stress relaxation of the barrier can for instance occur at elevated temperatures and result in severe dielectric deformation. Copper typically relaxes at elevated temperatures during thermal cycling and then builds-up thermal stress when cooled back to room temperature. However, the initial stress state can have a strong effect on the final microstructure. An example is shown here where a new growth mode, named 'super-secondary-grain-growth, is stress induced and leads to grains of many tens of microns. © 2006 American Institute of Physics.
Iacopi, F., Richard, O., Van Aelst, J., Mannaert, G., Talanov, V.V., Scherz, A., Schwartz, A.R., Bender, H., Travaly, Y., Brongersma, S.H., Antonelli, G.A., Moinpour, M. & Beyer, G. 2006, 'Understanding integration damage to low-k films: mechanisms and dielectric behaviour at 100kHz and 4GHz', Proceedings of the IEEE 2006 International Interconnect Technology Conference, pp. 12-14.
Iacopi, F., Brongersma, S.H., Mazurenko, A., Antonelli, G.A. & IEEE 2006, 'Use of SAWs for sub-micron detection of dielectric damage in interconnects for microelectronics', 2006 IEEE ULTRASONICS SYMPOSIUM, VOLS 1-5, PROCEEDINGS, pp. 269-272.
View/Download from: Publisher's site
Bruynseraede, C., Tokei, Z., Iacopi, F., Beyer, G.P., Michelon, J., Maex, K. & IEEE 2005, 'The impact of scaling on interconnect reliability', 2005 IEEE INTERNATIONAL RELIABILITY PHYSICS SYMPOSIUM PROCEEDINGS - 43RD ANNUAL, pp. 7-17.
View/Download from: Publisher's site
Besser, P.R., McKerrow, A.J., Iacopi, F., Wong, C.P. & Vlassak, J.J. 2005, 'Materials Research Society Symposium Proceedings: Preface', Materials Research Society Symposium Proceedings.
Hoofman, R.J.O.M., Verheijden, G.J.A.M., Michelon, J., Iacopi, F., Travaly, Y., Baklanov, M.R., Tokei, Z. & Beyer, G.P. 2005, 'Challenges in the implementation of low-k dielectrics in the back-end of line', MICROELECTRONIC ENGINEERING, pp. 337-344.
View/Download from: Publisher's site
Iacopi, F., Laknin, M., Mulloy, A., den Toonder, J.M.J., Vanhaeren, D. & Brongersma, S.H. 2005, 'On factors affecting the extraction of elastic modulus by nanoindentation of organic polymer films', Fundamentals of Nanoindentation and Nanotribology III, pp. 181-186.
Struyf, H., Hendrickx, D., Van Olmen, J., Iacopi, F., Richard, O., Travaly, Y., Van Hove, M., Boullart, W., Vanhaelemeersch, S. & IEEE 2005, 'Low-damage damascene patterning of SiOC(H) low-k dielectrics', Proceedings of the IEEE 2005 International Interconnect Technology Conference, pp. 30-32.
View/Download from: Publisher's site
Maex, K., Brongersma, S.H., Iacopi, F., Vanstreels, K., Travaly, Y., Baklanov, M., D'Haen, J., Beyer, G. & 2005, 'Aggressive scaling of Cu/low k: impact on metrology', Characterization and Metrology for ULSI Technology 2005, pp. 475-481.
Abell, T., Houthoofd, K., Iacopi, F., Grobet, P. & Maex, K. 2005, 'Solid state MAS NMR spectroscopic characterization of plasma damage and UV modification of low k dielectric films', Materials, Technology and Reliability of Advanced Interconnects-2005, pp. 35-40.
Iacopi, F., Brongersma, S.H., Mazurenko, A., Struyf, H., Mannaert, G., Travaly, Y., Maznev, A., Abell, T.J., Tower, J., Maex, K. & IEEE 2005, 'Surface Acoustic Waves as a technique for in-line detection of processing damage to low-k dielectrics', Proceedings of the IEEE 2005 International Interconnect Technology Conference, pp. 217-219.
View/Download from: Publisher's site
Richard, O., Iacopi, F., Tokei, Z. & Bender, H. 2005, 'Damage layer in silica-based low-k material induced by the patterning plasma process studied by energy-filtered TEM', Microscopy of Semiconducting Materials, pp. 347-350.
Tokei, Z., Sutcliffe, V., Demuynck, S., Iacopi, F., Roussel, P., Beyer, G.P., Hoofman, R.J.O.M., Maex, K. & ieee 2004, 'Impact of the barrier/dielectric interface quality on reliability of Cu porous-low-k interconnects', 2004 IEEE INTERNATIONAL RELIABILITY PHYSICS SYMPOSIUM PROCEEDINGS, pp. 326-332.
View/Download from: Publisher's site
Baklanov, M.R., Le, Q.T., Kesters, E., Iacopi, F., Van Aelst, J., Struyf, H., Boullart, W., Vanhaelemeersch, S., Maex, K. & IEEE 2004, 'Challenges of clean/strip processing for Cu/Low-k technology.', PROCEEDINGS OF THE IEEE 2004 INTERNATIONAL INTERCONNECT TECHNOLOGY CONFERENCE, pp. 187-189.
View/Download from: Publisher's site
Tokei, Z., Patz, M., Schmidt, M., Iacopi, F., Demuynck, S. & Maex, K. 2004, 'Correlation between barrier integrity and TDDB performance of copper porous low-k interconnects', MICROELECTRONIC ENGINEERING, pp. 70-75.
View/Download from: Publisher's site
Abell, T., Iacopi, F., Prokopowicz, G., Sun, B., Mazurenko, A., Travaly, Y., Baklanov, M., Jonas, A., Sullivan, C., Brongersma, S., Liou, H.C., Tower, J., Gostein, M., Gallagher, M., Calvert, J., Moinpour, M. & Maex, K. 2004, 'Comparison of modulus and density measurements by nanoindentation, SAWS, XRR and EP techniques of a porous low k MSQ dielectric', ADVANCED METALLIZATION CONFERENCE 2004 (AMC 2004), pp. 457-462.
Iacopi, F., Travaly, Y., Stucchi, M., Struyf, H., Peeters, S., Jonckheere, R., Leunissen, L.H.A., Tokei, Z., Sutcliffe, V., Richard, O., Van Hove, M. & Maex, K. 2004, 'Processing damage and electrical performance of porous dielectrics in narrow spaced interconnects', MATERIALS, TECHNOLOGY AND RELIABILITY FOR ADVANCED INTERCONNECTS AND LOW-K DIELECTRICS-2004, pp. 19-24.
Iacopi, F., Brongersma, S.H., Vandevelde, B., O'Toole, M., Degryse, D., Travaly, Y. & Maex, K. 2004, 'Challenges for structural stability of ultra-low-k-based interconnects', MICROELECTRONIC ENGINEERING, pp. 54-62.
View/Download from: Publisher's site
Iacopi, F., Degryse, D., Vos, I., Patz, M. & Maex, K. 2004, 'Understanding adhesion failure in low-k dielectric stack during chemical-mechanical polishing', THIN FILMS-STRESSES AND MECHANICAL PROPERTIES X, pp. 131-136.
Iacopi, F., Brongersma, S.H., Abell, T.J. & Maex, K. 2003, 'Buckling instabilities of thin cap layers deposited onto low-k dielectric films', POLYMER/METAL INTERFACES AND DEFECT MEDIATED PHENOMENA IN ORDERED POLYMERS, pp. 383-388.
Das, A., Le, Q.T., Furukawa, Y., Nguyen, V.H., Terzieva, V., de Theije, F., Whelan, C.M., Maenhoudt, M., Struyf, H., Tokei, Z., Iacopi, F., Stucchi, M., Carbonell, L., Vos, I., Bender, H., Patz, M., Beyer, G., Van Hove, M. & Maex, K. 2003, 'Characterisation of JSR's spin-on hardmask FF-02', MICROELECTRONIC ENGINEERING, pp. 308-313.
View/Download from: Publisher's site
Tokei, Z., Iacopi, F., Richard, O., Waeterloos, J., Rozeveld, S., Beach, E., Mebarki, B., Mandrekar, T., Guggilla, S. & Maex, K. 2003, 'Barrier studies on porous silk semiconductor dielectric', MICROELECTRONIC ENGINEERING, pp. 352-357.
View/Download from: Publisher's site
Ernur, D., Iacopi, F., Carbonell, L., Struyf, H. & Maex, K. 2003, 'Influence of low-k dry etch chemistries on the properties of copper and a Ta-based diffusion barrier', MICROELECTRONIC ENGINEERING, pp. 285-292.
View/Download from: Publisher's site
Iacopi, F., Patz, M., Vos, I., Tokei, Z., Sijmus, B., Le, Q.T., Sleeckx, E., Eyckens, B., Struyf, H., Das, A. & Maex, K. 2003, 'Impact of LKD5109 (TM) low-k to cap/liner interfaces in single damascene process and performance', MICROELECTRONIC ENGINEERING, pp. 293-301.
View/Download from: Publisher's site
Van Olmen, J., Wu, W., Van Hove, M., Travaly, Y., Brongersma, S.H., Eyckens, B., Maenhoudt, M., Van Aelst, J., Struyf, H., Demuynck, S., Tokei, Z., Vervoort, I., Sijmus, B., Vos, I., Ciofi, I., Stucchi, M., Maex, K., Iacopi, F., IEEE & IEEE 2003, 'Integration of Single Damascene 85/85 nm US copper trenches in Black Diamond using 193 nm optical lithography with dipole illumination', PROCEEDINGS OF THE IEEE 2003 INTERNATIONAL INTERCONNECT TECHNOLOGY CONFERENCE, pp. 171-173.
View/Download from: Publisher's site
Caluwaerts, R., Van Hove, M., Beyer, G., Hoofman, R.J.O.M., Struyf, H., Verheyden, G.J.A.M., Waeterloos, J., Tokei, Z., Iacopi, F., Carbonell, L., Le, Q.T., Das, A., Vos, I., Demuynck, S., Maex, K., IEEE & IEEE 2003, 'Post patterning meso porosity creation: A potential solution for pore sealing', PROCEEDINGS OF THE IEEE 2003 INTERNATIONAL INTERCONNECT TECHNOLOGY CONFERENCE, pp. 242-244.
View/Download from: Publisher's site
Iacopi, F., Zistl, C., Jehoul, C., Tokei, Z., Le, Q.T., Das, A., Sullivan, C., Prokopowicz, G., Gronbeck, D., Gallagher, M., Calvert, J. & Maex, K. 2002, 'Dependence of the minimal PVD TA(N) sealing thickness on the porosity of Zirkon (TM) LK dielectric films', MICROELECTRONIC ENGINEERING, pp. 351-360.
View/Download from: Publisher's site
Das, A., Kokubo, T., Furukawa, Y., Struyf, H., Vos, I., Sijmus, B., Iacopi, F., Van Aelst, J., Le, Q.T., Carbonell, L., Brongersma, S., Maenhoudt, M., Tokei, Z., Vervoort, I., Sleeckx, E., Stucchi, M., Schaekers, M., Boullart, W., Rosseel, E., Van Hove, M., Vanhaelemeersch, S., Shiota, A. & Maex, K. 2002, 'Characterisation and integration feasibility of JSR's low-k dielectric LKD-5109', MICROELECTRONIC ENGINEERING, pp. 25-33.
View/Download from: Publisher's site
Iacopi, F., Baklanov, M.R., Sleeckx, E., Conrad, T., Bender, H., Meynen, H. & Maex, K. 2002, 'Properties of porous HSQ-based films capped by plasma enhanced chemical vapor deposition dielectric layers', JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, pp. 109-115.
View/Download from: Publisher's site
Kokubo, T., Das, A., Furukawa, Y., Vos, I., Iacopi, F., Struyf, H., Aelst, J.V., Maenhoudt, M., Tokei, Z., Vervoort, I., Bender, H., Stucchi, M., Schaekers, M., Boullart, W., Van Hove, M., Vanhaelemeersch, S., Peterson, W., Shiota, A., Maex, K., IEEE & IEEE 2002, 'Cu/LKD-5109 damascene integration demonstration using FF-02 low-k spin-on hard-mask and embedded etch-stop', PROCEEDINGS OF THE IEEE 2002 INTERNATIONAL INTERCONNECT TECHNOLOGY CONFERENCE, pp. 51-53.
View/Download from: Publisher's site
Tokei, Z., Waeterloos, J.J., Iacopi, F., Caluwaerts, R., Struyf, H., Van Aelst, J. & Maex, K. 2001, 'Barrier process for damascene integration of developmental porous SiLK (TM) resin films', ADVANCED METALLIZATION CONFERENCE 2001 (AMC 2001), pp. 307-311.
Iacopi, F., Tokei, Z., Shamiryan, D., Le, Q.T., Malhouitre, S., Van Hove, M. & Maex, K. 2001, 'Overcoming barrier integrity issues of I-PVD Ta(N) layers on inorganic porous low-k's', ADVANCED METALLIZATION CONFERENCE 2001 (AMC 2001), pp. 61-66.
Waeterloos, J.J., Struyf, H., Van Aelst, J., Das, A., Caluwaerts, R., Alaerts, C., Boullart, W., Tökei, Z., Iacopi, F., Van Hove, M. & Maex, K. 2001, 'Damascene integration feasibility of developmental porous Silk resin films', Advanced Metallization Conference (AMC), pp. 19-24.
The integration of porous SiLK* resin (developmental version 7 or V7) in a single damascene architecture is discussed. Using this test vehicle an evaluation is made of in the impact of a substitution of a dense SiLK I 360 semiconductor dielectric fill by a porous SiLK (v7) film. The process sequence is reviewed and a process step analysis is made using scanning electron microscope (SEM) and transmission electron microscope analysis (TEM). Electrical results show that substitution of a dense SiLK film by a porous SiLK (v7) formulation is feasible. To investigate the influence of the pore size a comparison of a porous SiLK fill (developmental version 5, v5) and porous SiLK (v7) film is made. The presence of porosity has a direct impact on the Ta(N) barrier integrity. It is found that conventional ionized physical sputter techniques (I-PVD) do not provide the required side wall step coverage to cope with the roughness at the trench side wall induced by the presence of pores. Advanced I-PVD is showing more promise as improvements related to barrier integrity are observed. Finally the influence of film porosity on the chemical mechanical polishing (CMP) is investigated as a function of structure pattern density.
Iacopi, F., Donaton, R.A., Coenegrachts, B., Komiya, T., Struyf, H., Lepage, M., Van Aelst, J., Boullart, W., De Roest, D., Vos, I., Baklanov, M.R., Vereecke, G., Van Hove, M., Stucchi, M., Tokei, Z., Meynen, H., Bremmer, J.N., Vanhaelemeersch, S. & Maex, K. 2001, 'Studies on XLK (TM) film characterization and integration in copper damascene processes', ADVANCED METALLIZATION CONFERENCE 2000 (AMC 2000), pp. 287-293.
Shamiryan, D., Baklanov, M.R., Tokei, Z., Iacopi, F. & Maex, K. 2001, 'Evaluation of Ta(N) diffusion barrier integrity on porous low-K films', ADVANCED METALLIZATION CONFERENCE 2001 (AMC 2001), pp. 279-285.
Waeterloos, J.J., Struyf, H., Van Aelst, J., Castillo, D.W., Lucero, S., Caluwaerts, R., Alaerts, C., Mannaert, G., Boullart, W., Sleeckx, E., Schaekers, M., Tokel, Z., Vervoort, I., Steenbergen, J., Sijmus, B., Vos, I., Meuris, M., Iacopi, F., Donaton, R.A., Van Hove, M., Vanhaelemeersch, S. & Maex, K. 2001, 'Integration feasibility of porous SiLK semiconductor dielectric', Proceedings of the IEEE 2001 International Interconnect Technology Conference, IITC 2001, pp. 253-254.
View/Download from: Publisher's site
© 2000 IEEE. The feasibility of integrating a SiLK Semiconductor Dielectric film (trademark of The Dow Chemical Company) that contains closed pores was studied using a single damascene test vehicle. The study focussed on tool qualification, process set-up and single damascene feasibility to demonstrate technology extendibility. The results indicate that only minor changes have to be made to the process conditions when transitioning from a dense to a porous SiLK film.
Donaton, R.A., Iacopi, F., Baklanov, M.R., Shamiryan, D., Coenegrachts, B., Struyf, H., Lepage, M., Meuris, M., Van Hove, M., Gray, W.D., Meynen, H., De Roest, D., Vanhaelemeersch, S., Maex, K., IEEE & IEEE 2000, 'Physical and electrical characterization of silsesquioxane-based ultra-low k dielectric', PROCEEDINGS OF THE IEEE 2000 INTERNATIONAL INTERCONNECT TECHNOLOGY CONFERENCE, pp. 93-95.
View/Download from: Publisher's site
Pani, R., Pellegrini, R., Scopinaro, F., de Notaristefani, F., Pergola, A., De Vincentis, G., Soluri, A., Iacopi, F., Grammatico, A. & Del Guerra, A. 1996, 'Portable gamma camera for clinical use in nuclear medicine', IEEE Nuclear Science Symposium & Medical Imaging Conference, pp. 1170-1174.
Up today Hamamatsu R3292 is the Position Sensitive Photo Multiplier Tube (PSPMT) with the largest sensitive area (10 cm of diameter). At the same time it has the minimum size for clinical application in Nuclear Medicine. A portable gamma camera was realized, based on 5 inches PSPMT coupled to a scintillating array. The head has a light weight (15 Kg.) spatial resolution resulted better than that of Anger Camera with good linearity response, good energy resolution and FOV coincident with intrinsic one of PSPMT. To optimize gamma camera response two different scintillating arrays were tested: YAP:Ce and CsI (Tl). Their overall size cover all photocathode active area, and crystal pixel size was 2 mm2 mm. The detection efficiency resulted comparable to that of Anger Camera. The best result was obtained by CsI (Tl) scintillating: an intrinsic spatial resolution of 1.6 mm FWHM and a relative energy resolution of 17% FWHM. With a standard general purpose collimator a spatial resolution of about 2 mm resulted. Some preliminary results were also obtained in breast scintigraphy.

Journal articles

Kermany, A.R., Bennett, J.S., Valenzuela, V.M., Bowen, W.P. & Iacopi, F. 2017, 'Potential of epitaxial silicon carbide microbeam resonators for chemical sensing', Physica Status Solidi (A) Applications and Materials Science, vol. 214, no. 4, pp. 1-16.
View/Download from: Publisher's site
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Epitaxial silicon carbide is promising for chemical resonant sensing applications due to its excellent mechanical, thermal, and biochemical properties. This paper reviews six important aspects of (i) silicon carbide heteroepitaxial growth and residual stress; (ii) silicon carbide beam resonators, resonator types, and fabrication processes; (iii) sensing principles, dynamic sensing mechanical performance, and transduction techniques; (iv) damping parameters; (v) mean stress influence on mass sensitivity of SiC flexural microbridge resonators; and (vi) gradient stress impact on SiC cantilever static behavior. The primary goal is to suggest the means to improve the mass sensitivity parameter and application range of epitaxial silicon carbide microbeam resonators and benchmark it with other relevant materials.
Khan, Z.H., Kermany, A.R., Öchsner, A. & Iacopi, F. 2017, 'Mechanical and electromechanical properties of graphene and their potential application in MEMS', Journal of Physics D: Applied Physics, vol. 50, no. 5.
View/Download from: Publisher's site
© 2017 IOP Publishing Ltd. Graphene-based micro-electromechanical systems (MEMS) are very promising candidates for next generation miniaturized, lightweight, and ultra-sensitive devices. In this review, we review the progress to date of the assessment of the mechanical, electromechanical, and thermomechanical properties of graphene for application in graphene-based MEMS. Graphene possesses a plethora of outstanding properties - such as a 1 TPa Young's modulus, exceptionally high 2D failure strength that stems from its sp 2 hybridization, and strong sigma bonding between carbon atoms. Such exceptional mechanical properties can enable, for example, graphene-based sound sources capable of generating sound beyond the audible range. The recently engineered piezoelectric properties of atomic force microscope tip-pressed graphene membranes or supported graphene on SiO 2 substrates, have paved the way in fabricating graphene-based nano-generators and actuators. On the other hand, graphene's piezoresistive properties have enabled miniaturized pressure and strain sensors. 2D graphene nano-mechanical resonators can potentially measure ultralow forces, charges and potentially detect single atomic masses. The exceptional tribology of graphene can play a significant role in achieving superlubricity. In addition, the highest reported thermal conductivity of graphene is amenable for use in chips and providing better performing MEMS, as heat is efficiently dissipated. On top of that, graphene membranes could be nano-perforated to realize specialized applications like DNA translocation and desalination. Finally, to ensure stability and reliability of the graphene-based MEMS, adhesion is an important mechanical property that should be considered. In general, graphene could be used as a structural material in resonators, sensors, actuators and nano-generators with better performance and sensitivity than conventional MEMS.
Ahmed, M., Wang, B., Gupta, B., Boeckl, J.J., Motta, N. & Iacopi, F. 2017, 'On-Silicon Supercapacitors with Enhanced Storage Performance', JOURNAL OF THE ELECTROCHEMICAL SOCIETY, vol. 164, no. 4, pp. A638-A644.
View/Download from: Publisher's site
Mishra, N., Boeckl, J.J., Tadich, A., Jones, R.T., Pigram, P.J., Edmonds, M., Fuhrer, M.S., Nichols, B.M. & Iacopi, F. 2017, 'Solid source growth of graphene with Ni-Cu catalysts: Towards high quality in situ graphene on silicon', Journal of Physics D: Applied Physics, vol. 50, no. 9.
View/Download from: Publisher's site
© 2017 IOP Publishing Ltd. We obtain a monolayer graphene on epitaxial silicon carbide on silicon substrates via solid source growth mediated by a thin Ni-Cu alloy. Raman spectroscopy consistently shows an I D /I G band ratio as low as 0.2, indicating that the graphene obtained through this method is to-date the best quality monolayer grown on epitaxial silicon carbide films on silicon. We describe the key steps behind the graphene synthesis on the basis of extensive physical, chemical and morphological analyses. We conclude that (1) the oxidation, amorphisation and silicidation of the silicon carbide surface mediated by the Ni, (2) the liquid-phase epitaxial growth of graphene as well as (3) the self-limiting graphitization provided the molten Cu catalyst, are key characteristics of this novel synthesis method.
Amjadipour, M., MacLeod, J., Lipton-Duffin, J., Iacopi, F. & Motta, N. 2017, 'Epitaxial graphene growth on FIB patterned 3C-SiC nanostructures on Si (111): reducing milling damage.', Nanotechnology, vol. 28, no. 34, p. 345602.
View/Download from: Publisher's site
Epitaxial growth of graphene on SiC is a scalable procedure that does not require any further transfer step, making this an ideal platform for graphene nanostructure fabrication. Focused ion beam (FIB) is a very promising tool for exploring the reduction of the lateral dimension of graphene on SiC to the nanometre scale. However, exposure of graphene to the Ga(+) beam causes significant surface damage through amorphisation and contamination, preventing epitaxial graphene growth. In this paper we demonstrate that combining a protective silicon layer with FIB patterning implemented prior to graphene growth can significantly reduce the damage associated with FIB milling. Using this approach, we successfully achieved graphene growth over 3C-SiC/Si FIB patterned nanostructures.
Mishra, N., Boeckl, J., Motta, N. & Iacopi, F. 2016, 'Graphene growth on silicon carbide: A review', Physica Status Solidi (A) Applications and Materials Science, vol. 213, no. 9, pp. 2269-2269.
View/Download from: Publisher's site
Mishra, N., Boeckl, J., Motta, N. & Iacopi, F. 2016, 'Graphene growth on silicon carbide: A review', Physica Status Solidi (A) Applications and Materials Science, vol. 213, no. 9, pp. 2277-2289.
View/Download from: Publisher's site
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Graphene has been widely heralded over the last decade as one of the most promising nanomaterials for integrated, miniaturized applications spanning from nanoelectronics, interconnections, thermal management, sensing, to optoelectronics. Graphene grown on silicon carbide is currently the most likely candidate to fulfill this promise. As a matter of fact, the capability to synthesize high-quality graphene over large areas using processes and substrates compatible as much as possible with the well-established semiconductor manufacturing technologies is one crucial requirement. We review here, the enormous scientific and technological advances achieved in terms of epitaxial growth of graphene from thermal decomposition of bulk silicon carbide and the fine control of the graphene electronic properties through intercalation. Finally, we discuss perspectives on epitaxial graphene growth from silicon carbide on silicon, a particularly challenging area that could result in maximum benefit for the integration of graphene with silicon technologies.
Zarotti, F., Gupta, B., Iacopi, F., Sgarlata, A., Tomellini, M. & Motta, N. 2016, 'Time evolution of graphene growth on SiC as a function of annealing temperature', Carbon, vol. 98, pp. 307-312.
View/Download from: Publisher's site
© 2015 Elsevier Ltd. All rights reserved. We followed by X-ray Photoelectron Spectroscopy (XPS) the time evolution of graphene layers obtained by annealing 3C SiC(111)/Si(111) crystals at different temperatures. The intensity of the carbon signal provides a quantification of the graphene thickness as a function of the annealing time, which follows a power law with exponent 0.5. We show that a kinetic model, based on a bottom-up growth mechanism, provides a full explanation to the evolution of the graphene thickness as a function of time, allowing to calculate the effective activation energy of the process and the energy barriers, in excellent agreement with previous theoretical results. Our study provides a complete and exhaustive picture of Si diffusion into the SiC matrix, establishing the conditions for a perfect control of the graphene growth by Si sublimation.
Cooper, O., Wang, B., Brown, C.L., Tiralongo, J. & Iacopi, F. 2016, 'Toward Label-Free Biosensing with Silicon Carbide: A Review', IEEE Access, vol. 4, pp. 477-497.
View/Download from: Publisher's site
© 2013 IEEE. Recent innovation in microelectrical-mechanical systems (MEMSs) and plasmonics-based technologies has opened up perspectives for label-free sensing of biological and chemical analytes. Label-free sensing would enable increased sensitivity and miniaturization capabilities for biosensing devices. Silicon carbide is a semiconductor material that happens to possess ideal properties for augmenting both the MEMS/nanoelectromechanical systems and the plasmonics routes. It has remarkable chemical and biological inertness resulting in a high degree of biocompatibility, as well as pronounced mechanical resilience. In addition, it is an efficient (low loss) plasmonic metamaterial. Its cubic polytype can be grown on silicon wafers, allowing easy micromachining into building blocks for sensing devices, scalable to large volume production. Finally, silicon carbide is an ideal starting material for a controlled, wafer-scale growth of graphene, offering an additional wealth of excellent properties for nanosensing. The combination of all of these capabilities makes silicon carbide an outstanding material platform for the realization of label-free, analyte-specific, and highly sensitive biochemical molecule detection systems. These technologies will open exciting horizons in terms of high throughput, efficient drug screening, and early pathogen detection.
Pradeepkumar, A., Mishra, N., Kermany, A.R., Boeckl, J.J., Hellerstedt, J., Fuhrer, M.S. & Iacopi, F. 2016, 'Catastrophic degradation of the interface of epitaxial silicon carbide on silicon at high temperatures', Applied Physics Letters, vol. 109, no. 1.
View/Download from: UTS OPUS or Publisher's site
© 2016 Author(s). Epitaxial cubic silicon carbide on silicon is of high potential technological relevance for the integration of a wide range of applications and materials with silicon technologies, such as micro electro mechanical systems, wide-bandgap electronics, and graphene. The hetero-epitaxial system engenders mechanical stresses at least up to a GPa, pressures making it extremely challenging to maintain the integrity of the silicon carbide/silicon interface. In this work, we investigate the stability of said interface and we find that high temperature annealing leads to a loss of integrity. High-resolution transmission electron microscopy analysis shows a morphologically degraded SiC/Si interface, while mechanical stress measurements indicate considerable relaxation of the interfacial stress. From an electrical point of view, the diode behaviour of the initial p-Si/n-SiC junction is catastrophically lost due to considerable inter-diffusion of atoms and charges across the interface upon annealing. Temperature dependent transport measurements confirm a severe electrical shorting of the epitaxial silicon carbide to the underlying substrate, indicating vast predominance of the silicon carriers in lateral transport above 25 K. This finding has crucial consequences on the integration of epitaxial silicon carbide on silicon and its potential applications.
Wang, B., Ahmed, M., Wood, B. & Iacopi, F. 2016, 'All-solid-state supercapacitors on silicon using graphene from silicon carbide', Applied Physics Letters, vol. 108, no. 18.
View/Download from: Publisher's site
© 2016 Author(s). Carbon-based supercapacitors are lightweight devices with high energy storage performance, allowing for faster charge-discharge rates than batteries. Here, we present an example of all-solid-state supercapacitors on silicon for on-chip applications, paving the way towards energy supply systems embedded in miniaturized electronics with fast access and high safety of operation. We present a nickel-assisted graphitization method from epitaxial silicon carbide on a silicon substrate to demonstrate graphene as a binder-free electrode material for all-solid-state supercapacitors. We obtain graphene electrodes with a strongly enhanced surface area, assisted by the irregular intrusion of nickel into the carbide layer, delivering a typical double-layer capacitance behavior with a specific area capacitance of up to 174 F cm -2 with about 88% capacitance retention over 10 000 cycles. The fabrication technique illustrated in this work provides a strategic approach to fabricate micro-scale energy storage devices compatible with silicon electronics and offering ultimate miniaturization capabilities.
Gupta, B., Di Bernardo, I., Mondelli, P., Della Pia, A., Betti, M.G., Iacopi, F., Mariani, C. & Motta, N. 2016, 'Effect of substrate polishing on the growth of graphene on 3C-SiC(111)/Si(111) by high temperature annealing', Nanotechnology, vol. 27, no. 18.
View/Download from: Publisher's site
© 2016 IOP Publishing Ltd. We analyse the effects of substrate polishing and of the epilayer thickness on the quality of graphene layers grown by high temperature annealing on 3C-SiC(111)/Si(111) by scanning tunnelling microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, low energy electron diffraction and high resolution angle resolved photoemission spectroscopy. The results provide a comprehensive set of data confirming the superior quality of the graphene layers obtained on polished substrates, and the limitations of the growth obtained on unpolished surfaces.
Kermany, A.R., Bennett, J.S., Brawley, G.A., Bowen, W.P. & Iacopi, F. 2016, 'Factors affecting the f Q product of 3C-SiC microstrings: What is the upper limit for sensitivity?', Journal of Applied Physics, vol. 119, no. 5.
View/Download from: Publisher's site
© 2016 AIP Publishing LLC. The f n Q (Hz) is a crucial sensitivity parameter for micro-electro-mechanical sensing. We have recently shown a f n Q product of 10 12 Hz for microstrings made of cubic silicon carbide on silicon, establishing a new state-of-the-art and opening new frontiers for mass sensing applications. In this work, we analyse the main parameters influencing the frequency and quality factor of silicon carbide microstrings (material properties, microstring geometry, clamping condition, and environmental pressure) and investigate the potential for approaching the theoretical upper limit. We indicate that our previous result is only about a factor 2 lower than the thermoelastic dissipation limit. For fully reaching this upper limit, a substantial reduction of the defects in the silicon carbide thin film would be required, while maintaining a high residual tensile stress in the perfect-clamped strings.
Pradeepkumar, A., Mishra, N., Kermany, A.R., Boeckl, J.J., Hellerstedt, J., Fuhrer, M.S. & Iacopi, F. 2016, 'Response to 'Comment on 'Catastrophic degradation of the interface of epitaxial silicon carbide on silicon at high temperatures'', Applied Physics Letters, vol. 109, no. 19.
View/Download from: UTS OPUS or Publisher's site
Iacopi, F., Van Hove, M., Charles, M. & Endo, K. 2015, 'Power electronics with wide bandgap materials: Toward greener, more efficient technologies', MRS Bulletin, vol. 40, no. 5, pp. 390-395.
View/Download from: Publisher's site
© 2015 Materials Research Society. Greener technologies for more efficient power generation, distribution, and delivery in sectors ranging from transportation and generic energy supply to telecommunications are quickly expanding in response to the challenge of climate change. Power electronics is at the center of this fast development. As the efficiency and resiliency requirements for such technologies can no longer be met by silicon, the research, development, and industrial implementation of wide bandgap semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) are progressing at an unprecedented pace. This issue of MRS Bulletin, although certainly not exhaustive, provides an overview of the pace and quality of research revolving around GaN and SiC power electronics, from the choice of substrates, film growth, devices, and circuits to examples of applications.
Iacopi, F., Mishra, N., Cunning, B.V., Goding, D., Dimitrijev, S., Brock, R., Dauskardt, R.H., Wood, B. & Boeckl, J. 2015, 'A catalytic alloy approach for graphene on epitaxial SiC on silicon wafers', Journal of Materials Research, vol. 30, no. 5, pp. 609-616.
View/Download from: UTS OPUS or Publisher's site
© Materials Research Society 2015. We introduce a novel approach to the synthesis of high-quality and highly uniform few-layer graphene on silicon wafers, based on solid source growth from epitaxial 3C-SiC films. Using a Ni/Cu catalytic alloy, we obtain a transfer-free bilayer graphene directly on Si(100) wafers, at temperatures potentially compatible with conventional semiconductor processing. The graphene covers uniformly a 2 silicon wafer, with a Raman I D /I G band ratio as low as 0.5, indicative of a low defectivity material. The sheet resistance of the graphene is as low as 25 /square, and its adhesion energy to the underlying substrate is substantially higher than transferred graphene. This work opens the avenue for the true wafer-level fabrication of microdevices comprising graphene functional layers. Specifically, we suggest that exceptional conduction qualifies this graphene as a metal replacement for MEMS and advanced on-chip interconnects with ultimate scalability.
Gupta, B., Notarianni, M., Mishra, N., Shafiei, M., Iacopi, F. & Motta, N. 2015, 'Erratum: Corrigendum to ''Evolution of epitaxial graphene layers on 3C SiC/Si (111) as a function of annealing temperature in UHV'' [Carbon 68 (2014) 563-572]', Carbon, vol. 84, no. 1, p. 280.
View/Download from: Publisher's site
Ahmed, M., Khawaja, M., Notarianni, M., Wang, B., Goding, D., Gupta, B., Boeckl, J.J., Takshi, A., Motta, N., Saddow, S.E. & Iacopi, F. 2015, 'A thin film approach for SiC-derived graphene as an on-chip electrode for supercapacitors', Nanotechnology, vol. 26, no. 43.
View/Download from: Publisher's site
© 2015 IOP Publishing Ltd. We designed a nickel-assisted process to obtain graphene with sheet resistance as low as 80 square -1 from silicon carbide films on Si wafers with highly enhanced surface area. The silicon carbide film acts as both a template and source of graphitic carbon, while, simultaneously, the nickel induces porosity on the surface of the fil m by forming silicides during the annealing process which are subsequently removed. As stand-alone electrodes in supercapacitors, these transfer-free graphene-on-chip samples show a typical double-layer supercapacitive behaviour with gravimetric capacitance of up to 65 F g -1 . This work is the first attempt to produce graphene with high surface area from silicon carbide thin films for energy storage at the wafer-level and may open numerous opportunities for on-chip integrated energy storage applications.
Gupta, B., Placidi, E., Hogan, C., Mishra, N., Iacopi, F. & Motta, N. 2015, 'The transition from 3C SiC (1 1 1) to graphene captured by Ultra High Vacuum Scanning Tunneling Microscopy', Carbon, vol. 91, pp. 378-385.
View/Download from: Publisher's site
© 2015 Elsevier Ltd. All rights reserved. In this paper we clarify the transformation mechanism of 3C-SiC into graphene upon thermal decomposition, by a combination of high resolution Scanning Tunneling Microscopy (STM) images and first principle calculations. We studied the transition from 3C-SiC to graphene by high temperature annealing of C-terminated 3C SiC (1 1 1)/Si (1 1 1) samples in Ultra High Vacuum. By using STM we were able to observe very clear atomic resolution images of the transition from SiC (33)R30°to a new intermediate stage SiC (3/23)R30°(very close to the graphene (2 2) reconstruction) after annealing at 1250°C. We also obtained images of the transformation of the intermediate structure into a (1 1) monolayer graphene, caused by further sublimation of atoms in the subsurface layer. We have interpreted the results by using Density Functional Theory - Local Density Approximation calculations, which give full account of the SiC (33)R30°reconstruction, but fail to describe the SiC (3/23)R30°structure due to its incommensurability with the 3C-SiC (1 1 1) lattice.
Ranjbar Kermany, A. & Iacopi, F. 2015, 'Controlling the intrinsic bending of hetero-epitaxial silicon carbide micro-cantilevers', Journal of Applied Physics, vol. 118, no. 15.
View/Download from: Publisher's site
© 2015 AIP Publishing LLC. We introduce a simple methodology to predict and tailor the intrinsic bending of a cantilever made of a single thin film of hetero-epitaxial silicon carbide grown on silicon. The combination of our novel method for the depth profiling of residual stress with a few nm resolution with finite element modelling allows for the prediction of the bending behaviour with great accuracy. We also demonstrate experimentally that a silicon carbide cantilever made of one distinct film type can be engineered to obtain the desired degree of either upward, flat, or downward bending, by selecting the appropriate thickness and cantilever geometry. A precise control of cantilever bending is crucial for microelectrical mechanical system applications such as micro-actuators, micro-switches, and resonant sensors.
Cunning, B.V., Ahmed, M., Mishra, N., Kermany, A.R., Wood, B. & Iacopi, F. 2014, 'Graphitized silicon carbide microbeams: Wafer-level, self-aligned graphene on silicon wafers', Nanotechnology, vol. 25, no. 32.
View/Download from: Publisher's site
Currently proven methods that are used to obtain devices with high-quality graphene on silicon wafers involve the transfer of graphene flakes from a growth substrate, resulting in fundamental limitations for large-scale device fabrication. Moreover, the complex three-dimensional structures of interest for microelectromechanical and nanoelectromechanical systems are hardly compatible with such transfer processes. Here, we introduce a methodology for obtaining thousands of microbeams, made of graphitized silicon carbide on silicon, through a site-selective and wafer-scale approach. A Ni-Cu alloy catalyst mediates a self-aligned graphitization on prepatterned SiC microstructures at a temperature that is compatible with silicon technologies. The graphene nanocoating leads to a dramatically enhanced electrical conductivity, which elevates this approach to an ideal method for the replacement of conductive metal films in silicon carbide-based MEMS and NEMS devices. © 2014 IOP Publishing Ltd.
Mishra, N., Hold, L., Iacopi, A., Gupta, B., Motta, N. & Iacopi, F. 2014, 'Controlling the surface roughness of epitaxial SiC on silicon', Journal of Applied Physics, vol. 115, no. 20.
View/Download from: Publisher's site
The surface of cubic silicon carbide (3C-SiC) hetero-epitaxial films grown on the (111) surface of silicon is a promising template for the subsequent epitaxial growth of III-V semiconductor layers and graphene. We investigate growth and post-growth approaches for controlling the surface roughness of epitaxial SiC to produce an optimal template. We first explore 3C-SiC growth on various degrees of offcut Si(111) substrates, although we observe that the SiC roughness tends to worsen as the degree of offcut increases. Hence we focus on post-growth approaches available on full wafers, comparing chemical mechanical polishing (CMP) and a novel plasma smoothening process. The CMP leads to a dramatic improvement, bringing the SiC surface roughness down to sub-nanometer level, though removing about 200 nm of the SiC layer. On the other hand, our proposed HCl plasma process appears very effective in smoothening selectively the sharpest surface topography, leading up to 30% improvement in SiC roughness with only about 50 nm thickness loss. We propose a simple physical model explaining the action of the plasma smoothening. © 2014 AIP Publishing LLC.
Kermany, A.R., Brawley, G., Mishra, N., Sheridan, E., Bowen, W.P. & Iacopi, F. 2014, 'Microresonators with Q -factors over a million from highly stressed epitaxial silicon carbide on silicon', Applied Physics Letters, vol. 104, no. 8.
View/Download from: Publisher's site
We utilize the excellent mechanical properties of epitaxial silicon carbide (SiC) on silicon plus the capability of tuning its residual stress within a large tensile range to fabricate microstrings with fundamental resonant frequencies (f 0 ) of several hundred kHz and mechanical quality factors (Q) of over a million. The fabrication of the perfect-clamped string structures proceeds through simple silicon surface micromachining processes. The resulting f Q product in vacuum is equal or higher as compared to state-of-the-art amorphous silicon nitride microresonators. We demonstrate that as the residual epitaxial SiC stress is doubled, the f Q product for the fundamental mode of the strings shows a four-fold increase. © 2014 AIP Publishing LLC.
Gupta, B., Notarianni, M., Mishra, N., Shafiei, M., Iacopi, F. & Motta, N. 2014, 'Evolution of epitaxial graphene layers on 3C SiC/Si (1 1 1) as a function of annealing temperature in UHV', Carbon, vol. 68, pp. 563-572.
View/Download from: Publisher's site
The growth of graphene on SiC/Si substrates is an appealing alternative to the growth on bulk SiC for cost reduction and to better integrate the material with Si based electronic devices. In this paper, we present a thorough in situ study of the growth of epitaxial graphene on 3C SiC (1 1 1)/Si (1 1 1) substrates via high temperature annealing (ranging from 1125 to 1375 C) in ultra high vacuum (UHV). The quality and number of graphene layers have been investigated by using X-ray Photoelectron Spectroscopy (XPS), while the surface characterization have been studied by Scanning Tunnelling Microscopy (STM). Ex-situ Raman spectroscopy measurements confirm our findings, which demonstrate the exponential dependence of the number of graphene layers on the annealing temperature. © 2013 Elsevier Ltd. All rights reserved.
Stauss, S., Mori, S., Muneoka, H., Terashima, K. & Iacopi, F. 2013, 'Ashing of photoresists using dielectric barrier discharge cryoplasmas', Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures, vol. 31, no. 6.
View/Download from: Publisher's site
Plasma ashing of photoresists is a critical step in advanced microelectronics manufacturing as it often leads to extensive damage in porous organosilicate low - dielectrics and hinders the use of highly porous films in interconnects. To reduce plasma damage, the authors investigated the feasibility of ashing a 248-nm photoresist with cryoplasma. The authors ashed photoresist-coated silicon wafers with dielectric barrier discharge microplasma generated at temperatures of 170-291 K, a pressure of 100 Torr, applied voltages of V appl = 0.8 - 1.6 kV, and a frequency of f = 20 kHz in both Ar / O 2 and Ar / O 2 / N 2 gas mixtures. While the ashing rates at 170 K in Ar / O 2 decreased to about 20% of the ashing rates achieved at room temperature and 240 K, the addition of N 2 to the plasma gas enhanced the ashing rates by a factor of 1.5-2. Optical emission spectroscopy measurements of the plasmas showed that, in the Ar / O 2 / N 2 mixture, the main reactive species are N 2 radicals; x-ray photoelectron spectra of the ashed photoresists indicated that ashing is initiated from oxygen-containing functional groups of the photoresist. This study showed that decreased ashing rates at low plasma gas temperatures can be significantly enhanced by adjusting the plasma chemistry and that cryoplasma offers a viable process to minimize the damage from ashing of low - dielectric materials in interconnects, which will allow nanoelectronic devices to fully benefit from the introduction of such porous materials. © 2013 American Vacuum Society.
Iacopi, F., Brock, R.E., Iacopi, A., Hold, L. & Dauskardt, R.H. 2013, 'Evidence of a highly compressed nanolayer at the epitaxial silicon carbide interface with silicon', Acta Materialia, vol. 61, no. 17, pp. 6533-6540.
View/Download from: Publisher's site
Through a novel methodology for evaluating layer-by-layer residual stresses in epitaxial silicon carbide films with resolution down to 10 nm, we indicate the existence of a highly compressed interfacial nanolayer between the films and their silicon substrates. This layer is consistently present underneath all types of silicon carbide films examined herein, regardless of the extent of residual tensile stress measured in the full thickness of the films, which varies from 300 up to 1300 MPa. We link this nanolayer to the carbonization step of the film growth process and we discuss in detail the implications in terms of fracture behaviour by bulge testing of micromachined membranes.
Ma, S., Wang, S., Iacopi, F. & Huang, H. 2013, 'A resonant method for determining the residual stress and elastic modulus of a thin film', Applied Physics Letters, vol. 103, no. 3.
View/Download from: Publisher's site
By measuring the resonant frequencies of the first two symmetric vibration modes of a circular thin-film diaphragm and solving the Rayleigh-Ritz equation analytically, the residual stress and elastic modulus of the film were determined simultaneously. The results obtained employing this method are in excellent agreement with those obtained numerically in finite element modelling when tested using freestanding circular SiC diaphragms with residual tensile stress. The stress and modulus values are also in reasonably good agreement with those obtained from nanoindentation and wafer curvature measurements, respectively. © 2013 AIP Publishing LLC.
Iacopi, F., Walker, G., Wang, L., Malesys, L., Ma, S., Cunning, B.V. & Iacopi, A. 2013, 'Orientation-dependent stress relaxation in hetero-epitaxial 3C-SiC films', Applied Physics Letters, vol. 102, no. 1.
View/Download from: Publisher's site
Residual stresses in epitaxial 3C-SiC films on silicon, for chosen growth conditions, appear determined by their growth orientation. Stress evaluation locally with Raman spectroscopy, and across a 150 mm wafer with curvature measurements, indicate that thin films can be grown on Si(100) with residual tensile stresses as low as 150 MPa. However, films on Si(111) retain a considerably higher stress, around 900 MPa, with only minor decrease versus film thickness. Stacking faults are indeed geometrically a less efficient relief mechanism for the biaxial strain of SiC films grown on Si(111) with 111 orientation. Residual stresses can be tuned by the epitaxial process temperatures. © 2013 American Institute of Physics.
Iacopi, F., Choi, J.H., Terashima, K., Rice, P.M. & Dubois, G. 2011, 'Cryogenic plasmas for controlled processing of nanoporous materials.', Phys Chem Chem Phys, vol. 13, no. 9, pp. 3634-3637.
View/Download from: Publisher's site
Plasma processing at cryogenic temperatures tremendously suppresses the depth penetration of plasma radical species within nanoporous materials. We demonstrate that this confining effect is surprisingly unrelated to changes in the phase diffusivity of radical species gas, but is determined by the increase of the sticking coefficient and the radical recombination and reaction factors, favoring an early irreversible surface adsorption of the plasma radical species.
Wang, L., Dimitrijev, S., Han, J., Iacopi, F. & Zou, J. 2009, 'Transition between amorphous and crystalline phases of SiC deposited on Si substrate using H3SiCH3', Journal of Crystal Growth, vol. 311, no. 19, pp. 4442-4446.
View/Download from: Publisher's site
This paper presents a study of the transition between amorphous and crystalline phases of SiC films deposited on Si(1 0 0) substrate using H 3 SiCH 3 as a single precursor by a conventional low-pressure chemical vapor deposition method in a hot-wall reactor. The microstructure of SiC, characterized by X-ray diffraction and high-resolution transmission electron microscopy, is found to vary with substrate temperature and H 3 SiCH 3 pressure. The grain size decreases with increasing MS pressure at a given temperature and also decreases with reducing temperature at a given MS pressure. The deposition rates are exponentially dependent on the substrate temperature with the activation energy of around 2.6 eV. The hydrogen compositional concentration in the deposited SiC films, determined by secondary ion mass spectrometry depth profiling, is only 2.9% in the nanocrystalline SiC but more than 10% in the amorphous SiC, decreasing greatly with increasing deposition temperature. No hydride bonds are detected by Fourier transform infrared spectroscopy measurements. The chemical order of the deposited SiC films improves with increasing deposition temperature. © 2009 Elsevier B.V. All rights reserved.
Eslava, S., Kirschhock, C.E.A., Aldea, S., Baklanov, M.R., Iacopi, F., Maex, K. & Martens, J.A. 2009, 'Characterization of spin-on zeolite films prepared from Silicalite-1 nanoparticle suspensions', MICROPOROUS AND MESOPOROUS MATERIALS, vol. 118, no. 1-3, pp. 458-466.
View/Download from: Publisher's site
Eichhammer, Y., Roeck, J., Moelans, N., Iacopi, F., Blanpain, B. & Heyns, M. 2008, 'CALCULATION OF THE Au-Ge PHASE DIAGRAM FOR NANOPARTICLES', ARCHIVES OF METALLURGY AND MATERIALS, vol. 53, no. 4, pp. 1133-1139.
Eslava, S., Baklanov, M.R., Neimark, A.V., Iacopi, F., Kirschhock, C.E.A., Maex, K. & Martens, J.A. 2008, 'Evidence of large voids in pure-silica-zeolite low-k dielectrics synthesized by spin-on of nanoparticle suspensions', Advanced Materials, vol. 20, no. 16, pp. 3110-3116.
View/Download from: Publisher's site
A study was conducted to demonstrate that spin-on Silicalite-1 low-k films possess 0.55 nm Silicalite-1 micropores, and embedded voids of 2-5 nm and larger cavities in the range of tens of nanometers. The formation of cavities in the film occurs provided the content of residual silica from the synthesis does not suffice to fill the voids left between nanocrystals measuring 40-70nm. The higher the nanocrystal content of the suspension employed for spin-on, the larger the amount of embedded large voids. The experiment shows that spin-on Silicalite-1 films with k values below 3 contain a population of pores in the range of few tens of nanometers. The difficulty of sealing these wide voids represents a considerable and exciting challenge in the implementation of spin-on Silicalite-1 films as low-k dielectrics. The study concluded that the same properties are characteristic of other spin-on zeolite low-k films produced from zeolite nanocrstals dispersed in a precursor silica material.
Eslava, S., Eymery, G., Marsik, P., Iacopi, F., Kirschhock, C.E.A., Maex, K., Martens, J.A. & Baklanov, M.R. 2008, 'Optical property changes in low-k films upon ultraviolet-assisted curing', JOURNAL OF THE ELECTROCHEMICAL SOCIETY, vol. 155, no. 5, pp. G115-G120.
View/Download from: Publisher's site
Eslava, S., Delahaye, S., Baklanov, M.R., Iacopi, F., Kirschhock, C.E.A., Maex, K. & Martens, J.A. 2008, 'Reaction of trimethylchlorosilane in spin-on silicalite-1 zeolite film', LANGMUIR, vol. 24, no. 9, pp. 4894-4900.
View/Download from: Publisher's site
Iacopi, F., Richard, O., Eichhammer, Y., Bender, H., Vereecken, P.M., De Gendt, S. & Heyns, M. 2008, 'Size-dependent characteristics of indium-seeded Si nanowire growth', ELECTROCHEMICAL AND SOLID STATE LETTERS, vol. 11, no. 9, pp. K98-K100.
View/Download from: Publisher's site
Iacopi, F., Elia, C., Fournier, T., Sinapi, F. & Travaly, Y. 2008, 'Stress corrosion of organosilicate glass films in aqueous environments: Role of pH', JOURNAL OF MATERIALS RESEARCH, vol. 23, no. 3, pp. 862-868.
View/Download from: Publisher's site
Eslava, S., Iacopi, F., Urbanowicz, A.M., Kirschhock, C.E.A., Maex, K., Martens, J.A. & Baklanov, M.R. 2008, 'Ultraviolet-assisted curing of organosilicate glass low-k dielectric by excimer lamps', Journal of the Electrochemical Society, vol. 155, no. 11.
View/Download from: Publisher's site
A series of low- k films was exposed to UV-assisted curing (UV curing) with excimer lamps. The influence of the UV-curing wavelength, the UV-curing time, and the maximum pretreatment temperature were investigated. A mechanical, chemical, and optical characterization of this set of experiments is presented. It is revealed that the exposure to UV curing with 172 nm had sufficient energy to abundantly photodissociate Si-C H3 groups and to shrink the films. In turn, the elastic modulus was enhanced. As a side effect caused by the photodissociation of Si-CH 3 groups, the content of Si-OH and Si-H moieties increased. Longer wavelengths (222 and 308 nm) showed less-drastic effects on low- k films because they do not provide sufficient energy to photodissociate Si-CH 3 groups. This fundamental difference existing between different UV-curing wavelengths is evidenced by the optical characterization. Furthermore, this work also reveals the effect of pretreatment temperature on UV curing. Low pretreatment temperatures are required to keep enough photochemical reactivity and matrix mobility. © 2008 The Electrochemical Society.
Eslava, S., Urrutia, J., Busawon, A.N., Baklanov, M.R., Iacopi, F., Aldea, S., Maex, K., Martens, J.A. & Kirschhock, C.E.A. 2008, 'Zeolite-Inspired Low-k Dielectrics Overcoming Limitations of Zeolite Films', JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 130, no. 51, pp. 17528-17536.
View/Download from: Publisher's site
Eslava, S., Baklanov, M.R., Kirschhock, C.E.A., Iacopi, F., Aldea, S., Maex, K. & Martens, J.A. 2007, 'Characterization of a molecular sieve coating using ellipsometric porosimetry', LANGMUIR, vol. 23, no. 26, pp. 12811-12816.
View/Download from: Publisher's site
Griffiths, H., Xu, C., Barrass, T., Cooke, M., Iacopi, F., Vereecken, P. & Esconjauregui, S. 2007, 'Plasma assisted growth of nanotubes and nanowires', SURFACE & COATINGS TECHNOLOGY, vol. 201, no. 22-23, pp. 9215-9220.
View/Download from: Publisher's site
Iacopi, F., Vereecken, P.M., Schaekers, M., Caymax, M., Moelans, N., Blanpain, B., Richard, O., Detavernier, C. & Griffiths, H. 2007, 'Plasma-enhanced chemical vapour deposition growth of Si nanowires with low melting point metal catalysts: an effective alternative to Au-mediated growth', NANOTECHNOLOGY, vol. 18, no. 50.
View/Download from: Publisher's site
Richard, O., Iacopi, F., Bender, H. & Beyer, G. 2007, 'Sidewall damage in silica-based low-k material induced by different patterning plasma processes studied by energy filtered and analytical scanning TEM', MICROELECTRONIC ENGINEERING, vol. 84, no. 3, pp. 517-523.
View/Download from: Publisher's site
Iacopi, F., Beyer, G., Travaly, Y., Waldfried, C., Gage, D.M., Dauskardt, R.H., Houthoofd, K., Jacobs, P., Adriaensens, P., Schulze, K., Schulz, S.E., List, S. & Carlotti, G. 2007, 'Thermomechanical properties of thin organosilicate glass films treated with ultraviolet-assisted cure', ACTA MATERIALIA, vol. 55, no. 4, pp. 1407-1414.
View/Download from: Publisher's site
Eslava, S., Iacopi, F., Baklanov, M.R., Kirschhock, C.E.A., Maex, K. & Martens, J.A. 2007, 'Ultra-violet-assisted cure of spin-on silicalite-1 films', FROM ZEOLITES TO POROUS MOF MATERIALS: THE 40TH ANNIVERSARY OF INTERNATIONAL ZEOLITE CONFERENCE, PROCEEDINGS OF THE 15TH INTERNATIONAL ZEOLITE CONFERENCE, vol. 170, pp. 594-599.
Eslava, S., Iacopi, F., Baklanov, M.R., Kirschhock, C.E.A., Maex, K. & Martens, J.A. 2007, 'Ultraviolet-assisted curing of polycrystalline pure-silica zeolites: Hydrophobization, functionalization, and cross-linking of grains', Journal of the American Chemical Society, vol. 129, no. 30, pp. 9288-9289.
View/Download from: Publisher's site
We demonstrate the advantageous use of an ultraviolet-assisted curing for the preparation of polycrystalline zeolites. The ultraviolet-assisted curing effectively hydrophobizes the porous structure of a spin-on Silicalite-1 film by means of silanol condensation and grafting of desorbing organic template fragments. Moreover, it enhances the packing of the grains, so the intergrain voids are substantially shrunk and the mechanical properties improved. Copyright © 2007 American Chemical Society.
Travaly, Y., Bamal, M., Carbonell, L., Iacopi, F., Stucchi, M., Van Hove, M. & Beyer, G.P. 2006, 'A novel approach to resistivity and interconnect modeling', MICROELECTRONIC ENGINEERING, vol. 83, no. 11-12, pp. 2417-2421.
View/Download from: Publisher's site
Iacopi, F., Travaly, Y., Van Hove, M., Jonas, A.M., Molina-Aldareguia, J.M., Elizalde, M.R. & Ocana, I. 2006, 'Extent of plasma damage to porous organosilicate films characterized with nanoindentation, x-ray reflectivity, and surface acoustic waves', JOURNAL OF MATERIALS RESEARCH, vol. 21, no. 12, pp. 3161-3167.
View/Download from: Publisher's site
Giangrandi, S., Brijs, B., Sajavaara, T., Bender, H., Iacopi, F., Vantomme, A. & Vandervorst, W. 2006, 'Irradiation-induced damage in porous low-k materials during low-energy heavy-ion elastic recoil detection analysis', NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, vol. 249, pp. 189-192.
View/Download from: Publisher's site
Iacopi, F., Travaly, Y., Eyckens, B., Waldfried, C., Abell, T., Guyer, E.P., Gage, D.M., Dauskardt, R.H., Sajavaara, T., Houthoofd, K., Grobet, P., Jacobs, P. & Maex, K. 2006, 'Short-ranged structural rearrangement and enhancement of mechanical properties of organosilicate glasses induced by ultraviolet radiation', JOURNAL OF APPLIED PHYSICS, vol. 99, no. 5.
View/Download from: Publisher's site
Iacopi, F., Stucchi, M., Richard, O. & Maex, K. 2004, 'Electrical equivalent sidewall damage in patterned low-k dielectrics', ELECTROCHEMICAL AND SOLID STATE LETTERS, vol. 7, no. 4, pp. G79-G82.
View/Download from: Publisher's site
Shamiryan, D., Abell, T., Iacopi, F. & Maex, K. 2004, 'Low-k dielectric materials', Materials Today, vol. 7, no. 1, pp. 34-39.
View/Download from: Publisher's site
The integration of low dielectric constant (k) materials in microelectronic circuits was discussed. The various ways to reduce the dielectric constant of materials were also discussed. The studies show that the dielectric constant of materials can be reduced by selecting chemical bonds with low polarizability and by introducing porosity. The thermal, chemical, physical and mechanical stability requirements, as well as the reliability criteria that must be met by low-k materials, for their application in microelectronic circuits, were also discussed.
Shamiryan, D., Abell, T., Iacopi, F. & Maex, K. 2004, 'Low-k dielectric materials', MATERIALS TODAY, vol. 7, no. 1, pp. 34-39.
View/Download from: Publisher's site
Iacopi, F., Tokei, Z., Stucchi, M., Brongersma, S.H., Vanhaeren, D. & Maex, K. 2003, 'Characterization of porous structure in ultra-low-k dielectrics by depositing thin conductive cap layers', MICROELECTRONIC ENGINEERING, vol. 65, no. 1-2, pp. 123-131.
View/Download from: Publisher's site
Maex, K., Baklanov, M.R., Shamiryan, D., Iacopi, F., Brongersma, S.H. & Yanovitskaya, Z.S. 2003, 'Low dielectric constant materials for microelectronics', JOURNAL OF APPLIED PHYSICS, vol. 93, no. 11, pp. 8793-8841.
View/Download from: Publisher's site
Iacopi, F., Tokei, Z., Stucchi, M., Lanckmans, F. & Maex, K. 2003, 'Diffusion barrier integrity and electrical performance of Cu/porous dielectric damascene lines', IEEE ELECTRON DEVICE LETTERS, vol. 24, no. 3, pp. 147-149.
View/Download from: Publisher's site
Iacopi, F., Brongersma, S.H. & Maex, K. 2003, 'Compressive stress relaxation through buckling of a low-k polymer-thin cap layer system', APPLIED PHYSICS LETTERS, vol. 82, no. 9, pp. 1380-1382.
View/Download from: Publisher's site
Shamiryan, D., Baklanov, M.R., Yanovitskaya, Z.S., Zverev, A.V., Tokei, Z., Iacopi, F. & Maex, K. 2003, 'Evaluation of thin Ta(N) film integrity deposited on porous glasses', OPTICA APPLICATA, vol. 33, no. 1, pp. 91-96.
Ageron, M., Albert, A., Barvich, T., Beaumont, W., Beckers, T., Bernier, K., Blüm, P., Boulogne, I., Bouvet, D., Brom, J.M., Charles, F., Coffin, J., Contardo, D., Daubie, E., Didierjean, F., De Lentdecker, G., De Troy, J., Devroede, O., Erdmann, M., Ernenwein, J.P., Fahrer, M., Flügge, G., Fontaine, J.C., Geist, W., Goerlach, U., Gottschalk, M., Helleboid, J.M., Huss, D., Iacopi, F., Juillot, P., Kärcher, K., Kühn, F., Lounis, A., Maazouzi, C., Macke, D., Martin, C., Mirabito, L., Moreau, S., Müller, T., Neuberger, D., Nowack, A., Perries, S., Ripp-Baudot, I., Röderer, F., Schulte, R., Shekhtman, L., Simonis, H.J., Struczinski, W., Tatarinov, A., Thümmel, W.H., Udo, F., Vander Velde, C., Van Doninck, W., Van Dyck, C., Vanlaer, P., Van Lancker, L., Weiler, T., Zander, A., Zghiche, A. & Zhukov, V. 2002, 'Experimental and simulation study of the behaviour and operation modes of MSGC + GEM detectors', Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 489, no. 1-3, pp. 121-139.
View/Download from: Publisher's site
A small series production of detector modules made of MicroStrip Gas Counters (MSGC) and a Gas Electron Multiplier (GEM) foil has been exposed to a high-intensity hadron beam. We report about the reproductibility and stability of the detector responses and about the occurrence and consequences of discharges in the detector. The interdependence of the four voltage differences used in the detector has been studied by simulation and with X-ray measurements. Rate dependence of the signal amplitude is observed. The behaviour of the MSGC+GEM is compared to that of a state-of-the-art MSGC. Influence of various parameters on the detector response is investigated. © 2002 Elsevier Science B.V. All rights reserved.
Iacopi, F., Tokei, Z., Le, Q.T., Shamiryan, D., Conard, T., Brijs, B., Kreissig, U., Van Hove, M. & Maex, K. 2002, 'Factors affecting an efficient sealing of porous low-k dielectrics by physical vapor deposition Ta(N) thin films', JOURNAL OF APPLIED PHYSICS, vol. 92, no. 3, pp. 1548-1554.
View/Download from: Publisher's site
Iacopi, F., Devroede, O., Pins, R., Van Hoof, R., Honore, M., Zhukov, V., Van Lancker, L., Van Doninck, W. & Beyne, E. 2001, 'An optimized process for the production of advanced planar wire grid plates as detectors for high energy physics experiments', SENSORS AND ACTUATORS A-PHYSICAL, vol. 93, no. 1, pp. 76-83.
View/Download from: Publisher's site
Ageron, M., Albert, A., Barvich, T., Beaumont, W., Beckers, T., Bernier, K., Blüm, P., Bouhali, O., Boulogne, I., Bouvet, D., Brom, J.M., Charles, F., Coffin, J., Contardo, D., Daubie, E., Didierjean, F., Erdmann, M., De Lentdecker, G., Devroede, O., De Troy, J., Ernenwein, J.P., Fahrer, M., Flügge, G., Fontaine, J.C., Geist, W., Goerlach, U., Gottschalk, M., Helleboid, J.M., Huss, D., Iacopi, F., Kärcher, K., Kühn, F., Juillot, P., Lounis, A., Maazouzi, C., Macke, D., Martin, C., Mirabito, L., Moreau, S., Müller, T., Neuberger, D., Nowack, A., Perries, S., Ripp-Baudot, I., Röderer, F., Schulte, R., Shekhtman, L., Simonis, H.J., Struczinski, W., Tatarinov, A., Thümmel, W.H., Udo, F., Van Doninck, W., Van Dyck, C., Vander Velde, C., Vanlaer, P., Van Lancker, L., Weiler, T., Zander, A., Zghiche, A. & Zhukov, V. 2001, 'Robustness test of a system of MSGC+GEM detectors at the cyclotron facility of the Paul Scherrer institute', Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 471, no. 3, pp. 380-391.
View/Download from: Publisher's site
A system of detector modules consisting of a large size Gas Electron Multiplier (GEM), coupled to Micro Strip Gas Counters (MSGC), has been exposed to a pion beam at the Paul Scherrer Institute Cyclotron facility. As part of a CMS tracker milestone, the aim of this test was to investigate the robustness of such detectors when exposed to experimental conditions close to what is expected at the Large Hadron Collider (LHC) of CERN. Eighteen detector modules have been operated at voltage settings corresponding to 98% detection efficiency for Minimum Ionizing Particles during a period of 5 weeks. Sparking rates and strip losses have been monitored throughout the exposure. An operation margin of at least a factor of three with respect to the required gas gain has been demonstrated. © 2001 Elsevier Science B.V. All rights reserved.
Maini, C.L., de Notaristefani, F., Tofani, A., Iacopi, F., Sciuto, R., Semprebene, A., Malatesta, T., Vittori, F., Frezza, F., Botti, C., Giunta, S. & Natali, P.G. 1999, '99mTc-MIBI scintimammography using a dedicated nuclear mammograph.', J Nucl Med, vol. 40, no. 1, pp. 46-51.
UNLABELLED: This study reports on a prototype single-photon emission mammograph (SPEM) dedicated to 99mTc-hexakis-2-methoxyisobutile isonitrile (MIBI) scintimammography. Main technical features are reported together with physical performance. Preliminary patient data are also reported. METHODS: The SPEM detector head is composed of a CsI(T1) scintillating array coupled to a Hamamatsu R3292 position-sensitive photomultiplier tube with crossed-wire anode. The high-resolution collimator is 35-mm thick with a 1.7-mm hole diameter and a 0.2-mm septal thickness. The electronic acquisition system is composed of five integrated cards with computation based on high-speed programmable microprocessors. The readout electronics include correction maps for on-line energy correction and spatial uniformity. The small size of the detector head allows the use of mechanical breast compression to minimize detection distance and tissue scatter. After physical SPEM performance evaluation in vivo scintimammography was performed in 29 patients and was compared with a state-of-the-art Anger camera. RESULTS: The SPEM showed an intrinsic spatial resolution of 2 mm, an energy resolution of 23% FWHM at 122 keV and spatial uniformities of 18% (integral) and 13.5% (differential). The SPEM imaged one 0.4-cm carcinoma missed by the Anger camera and resolved as separate lumps an irregular focal uptake on the Anger camera image. The remaining cases yielded concordant results. CONCLUSION: The SPEM prototype presented in this study shows adequate physical characteristics for 99mTc-MIBI scintimammography.
Maini, C.L., de Notaristefani, F., Tofani, A., Iacopi, F., Sciuto, R., Semprebene, A., Malatesta, T., Vittori, F., Frezza, F., Botti, C., Giunta, S. & Natali, P.G. 1999, 'Tc-99m-MIBI scintimammography using a dedicated nuclear mammograph', JOURNAL OF NUCLEAR MEDICINE, vol. 40, no. 1, pp. 46-51.
De Notaristefani, F., Iacopi, F., Leonetti, C., Maini, C.L., Malatesta, T., Malì, P., Semprebene, A., Torrioli, S., Tüma, L. & Vittori, F. 1998, 'A YAP camera 40 40 mm2 with fast readout electronics', IEEE Transactions on Nuclear Science, vol. 45, no. 5, pp. 2302-2308.
View/Download from: Publisher's site
Previous papers have already demonstrated the suitability, for single-photon emission computed tomography (SPECT) tracers biodistribution studies on small animals, of a miniature gamma camera composed by a YAP:Ce scintillating array 4 4 1 cm 3 coupled to a 3-in Hamamatsu crossed-wire anode position sensitive photomultiplier (PSPMT). Some modifications have been applied to the imaging system readout in order to adapt its utilization for specific purposes (i.e., SPECT radiopharmaceutical testing) and to reduce construction costs so that a larger scale production may be feasible. In particular, the system introduced here is based on a resistive chain readout and an integrated acquisition electronics. The intrinsic performance of this new version has been analyzed and compared to the previous system, which had a single-wire readout. Results showed that the basic characteristics of the imaging system remain substantially unchanged in this simplified version, while a faster count rate is achieved. A test on a biological sample performed with the YAP camera both in single-wire and in resistive chain readout modality is also presented, which shows the system high performance in comparison to the Anger camera. © 1998 IEEE.
Pani, R., Pellegrini, R., Scopinaro, F., Soluri, A., De Vincentis, G., Pergola, A., Iacopi, F., Corona, A., Grammatico, A., Filippi, S. & Ballesio, P.L. 1997, 'Scintillating array gamma camera for clinical use', Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 392, no. 1-3, pp. 295-298.
View/Download from: Publisher's site
Dedicated gamma cameras for specific clinical application are representing a new trend in Nuclear Medicine. They are based on Position Sensitive Photo Multiplier Tubes (PSPMT). The main intrinsic limitation of large area PSPMT (5 diameter) is the photocathode glass window. Coupling to a planar scintillation crystal strongly affects the useful active area and the intrinsic spatial resolution. To overcome this limitation at University of Rome "La Sapienza" was developed the first 5 diameter gamma camera consisting of a Hamamatsu R3292 PSPMT coupled to 50 x 50 YAP: Ce scintillating array. The array pixel size is 2 x 2 mm 2 and the overall dimension of multi-crystal is 10 x 10 x 1 cm 3 . Resistive chains were used to calculate the centroid. The scintillating array produces a focused light spot minimising the spread introduced by PSPMT glass window. The intrinsic spatial resolution varied between 2 and 2.7 mm. The position linearity and useful active area resulted in good agreement with intrinsic one obtained by light spot irradiation. The real limitation was the poor energy resolution of an individual crystal (40%) and the poor uniformity response of PSPMT (within ± 15%). A correction matrix was then carried out by which a 57% of total energy resolution was obtained for the whole matrix. The camera is currently operating as Single Photon Emission Mammography (SPEM) and it is producing breast functional images for malignant tumour detection using the same geometry as standard X-ray mammography.
Iacopi, F., Gould, T., Boeckl, J.J., Mishra, N., Goding, D., Pradeepkumar, A., Cunning, B.V., Wood, B., Brock, R.E., Dauskardt, R.H. & Dimitrijev, S., 'Graphene as a p-type metal for ultimate miniaturization'.
We report macroscopic sheets of highly conductive bilayer graphene with exceptionally high hole concentrations of ~ $10^{15}$ $cm^{-2}$ and unprecedented sheet resistances of 20-25 {\Omega} per square over macroscopic scales, and obtained in-situ over a thin cushion of molecular oxygen on a silicon substrate. The electric and electronic properties of this specific configuration remain stable upon thermal anneals and months of exposure to air. We further report a complementary ab-initio study, predicting an enhancement of graphene adhesion energy of up to a factor 20, also supported by experimental fracture tests. Our results show that the remarkable properties of graphene can be realized in a reliable fashion using a high-throughput process. In addition to providing exceptional material properties, the growth process we employed is scalable to large areas so that the outstanding conduction properties of graphene can be harnessed in devices fabricated via conventional semiconductor manufacturing processes. We anticipate that the approach will provide the necessary scalability and reliability for future developments in the graphene nanoscience and technology fields, especially in areas where further miniaturization is hampered by size effects and electrical reliability of classical conductors.
  • Air Force Research Laboratory
  • Naval Research Laboratory
  • Army Research Laboratory