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Fabrication of nanostructures by means of Block Copolymer based lithography

Fabrication of nanostructures by means of Block Copolymer based lithography. Monica Ceresoli Supervisor: Prof. Paolo Milani Co-Supervisor: Dr. Michele Perego. Introduction. 2015 10 nm. 2013 14 nm. 2003 90 nm. 2005 65 nm. 2009 32nm. 2011 22 nm. 2007 45 nm. Manifacturing.

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Fabrication of nanostructures by means of Block Copolymer based lithography

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  1. Fabrication of nanostructures by means of Block Copolymer based lithography Monica CeresoliSupervisor: Prof. Paolo MilaniCo-Supervisor: Dr. Michele Perego

  2. Introduction 2015 10 nm 2013 14 nm 2003 90 nm 2005 65 nm 2009 32nm 2011 22 nm 2007 45 nm Manifacturing Development Research Fabrication issue: sub 20 nm structures • Requirements: • High density • Long range order • Simple and short process Implementation of self-assembling materials in Microelectronics lithography. ITRS 2011 Edition: “Emerging Research Materials”

  3. Introduction BLOCK COPOLYMERS (BCP): class of macromolecules produced by covalently bonding two or more chemically distinct polymer blocks. Thermodynamic Incompatibility + Covalent Bond Lamellae Thermal treatment Phase separation in ordered nano-domains I.Botiz et al., Materials Today 13, 42-51 (2010), F. S. Bates et al., Physics Today 52, 32-38 (1999)

  4. Introduction Lithographic application of Lamellar thin films. • Problems: • Long time process. • Weakdependence on Temperature and time of annealing. • Small dimension of ordereddomains (correlationlengthξ) • Requirements: • High density • Long range order • Simple and short process Correlation length ξ (nm) Correlation length ξ (nm) Furnace 100 minutes Annealing time (min) Annealing temperature (°C) R. Ruiz et al., Adv. Mater. 2007, 19, 2157–2162, R. Ruiz et al., Adv. Mater. 19, 587–591 (2007)

  5. Introduction Lithographic application of Lamellar thin films. • Problems: • Long time process. • Weakdependence on Temperature and time of annealing. • Small dimension of ordereddomains (correlationlengthξ) • Requirements: • High density • Long range order • Simple and short process New study: Thermodynamics on short time-scale R. Ruiz et al., Adv. Mater. 2007, 19, 2157–2162, R. Ruiz et al., Adv. Mater. 19, 587–591 (2007)

  6. Materials and Techniques Preparation of lamellar thin films. • Neutralization of the substrate. SiO2 Random Copolymer Si

  7. Materials and Techniques Preparation of lamellar thin films. • Neutralization of the substrate. Poly (Styrene-block-Methyl Methacrylate) • Block Copolymer deposition. 50% PMMA 50% PS Block Copolymer SiO2 Random Copolymer Si

  8. Materials and Techniques Preparation of lamellar thin films. • Neutralization of the substrate. • Block Copolymer deposition. • Thermal treatment. Block Copolymer SiO2 Random Copolymer Si

  9. Materials and Techniques • Slow heating and coolingramp. • Impossibility to fine-tuning the rate of thermalenergytransferred to the sample. Standard thermal process in furnace : Hours! • Fast heating and cooling ramp. • Real time –control of sample temperature. • Temperatures up above 300°C. Novel approach with Rapid Thermal Processing: Seconds! Steady state Cooling ramp Heating ramp Temperature (°C) Samples are heated by halogen lamps irradiation. Time (s) F. Ferrarese Lupi et al., Nanotechnology, 24 (2013) 315601

  10. Experimental Results Increasing the annealing temperature more and more ordered films get formed. 60s of annealing Temperature M. Ceresoli et al., 2013, submitted.

  11. Experimental Results Significant variations of the correlation length (ξ) have been observed. 60s treatment 10s treatment Temperature (°C) M. Ceresoli et al., 2013, submitted.

  12. Experimental Results Two times higher ξ in respect to literature results. 60s treatment 10s treatment 100 minutes conventionalfurnace 1minute in RTP time of processreduced by twoorders of magnitude ? Temperature (°C) R. Ruiz et al., Adv. Mater. 2007, 19, 2157–2162

  13. Experimental Results 15m 60s 5m 10s 1s 5s RTP 290°C Time of annealing 290°C 270°C 250°C Correlation length ξ (nm) time (s) R. Ruiz et al., Adv.Mater. 2007,19, 587-591, S. Ji, P.F. Nealey et al., Macrom. (2011) 44.4291.

  14. Experimental Results A double phase appears! Selective remotion of PMMA phase 100 nm Residual solvent at the interface with the substrate F. Ferrarese Lupi et al., Nanotechnology, 24 (2013) 315601 FFT 100 nm

  15. Experimental Results 15m 60s 5m 10s 1s 5s RTP 290°C Time of annealing Solvent content cylinders drive order 290°C Correlation length ξ (nm) 1 10 100 1000 Time (s) Time (s) On courtesy of Prof. M. Laus, Università del Piemonte Orientale

  16. Perspectives and Open Points Morphology investigation with Grazing Incident Small Angle X-ray Scattering. Analysis in progress…

  17. Perspectives and Open Points The presence of a double phase is affected by solvent choise… PS selective PMMA selective Boiling Temperature of solvent ? Chloroform THF Acetone Toluene 20 nm 20 nm 1min, 250°C, RTP

  18. Perspectives and Open Points In very fast thermal treatment, heating and cooling ramps become relevant… Steady state Correlation length (nm) Cooling ramp Heating ramp Temperature (°C) Heating rate (°C/s) • No significant variation for steady state as long as 30 s. • What about 5 s or 1 s of steady state? Time (s)

  19. Pubblications • Rapid Thermal Processing of self-assemblingblockcopolymerthinfilms • F. Ferrarese Lupi, T.J. Giammaria, M. Ceresoli, G. Seguini, K. Sparnacci, D. Antonioli, V. Gianotti, M. Laus • and M. Perego. Nanotechnology, 24 (2013) 315601. • Higlyorderedlamellarpatterns in symmetricblockcopolymerthinfilms • M.Ceresoli, F.Ferrarese Lupi, G.Seguini, K. Sparnacci, V. Gianotti, D. Antonioli, M. Laus, L. Boarino • and M. Perego. submitted. • Flash Grafting of Functional Random Copolymers for surfaceneutralization • F. Ferrarese Lupi, T.J. Giammaria, G. Seguini, M. Ceresoli, M. Perego, D. Antonioli, V. Gianotti, K. Sparnacci • and M. Laus. submitted. Conferences • EPF2013 EuropeanCongress of Polymers, Pisa, June16th-21th 2013. • Stabilization of mixedmorphology in BlockCopolymerthinfilms by solvent • assistedthermal processing. • Poster presentation

  20. Fabrication of nanostructures by means of blockcopolymerbasedlithography Thank you for your attention. Monica Ceresoli 15/10/2013

  21. Technologies under study

  22. Residual solvent Residual solvent locally trapped at the interface between random and block copolymer. "local" toluene rich interphase. Toluene amount in the block layer in the absence of random is 0,083 ng mm-2nm-1.

  23. Correlation length SEM images are mapped through a intensity gradient function. Gradient vector of intensity correlation function Extraction of correlation length ξ C. Harrison et al, ,Macromolecules 33, 857-65

  24. Optimization of RTP How to get an effective plateau … setting an overheating in the nominal temperature, the radiative power of infrared lamps can keep the temperature costant. • This assures control on very short thermal treatments too (from minutes to seconds). • Study of the Early stages of self-assembling evolution in symmetric PS-b-PMMA thin films

  25. Materials and Techniques Samples preparation • Neutralization of the substrate. • Block Copolymer deposition. • Thermal treatment for self-assembling. • Remotion of PMMA • Acquisition of images by SEM Block Copolymer Random Copolymer SiO2 Si

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