Surface Engineering Nanostructures
Low energy Ion bombardment nanostructuring Process
Fernando Alvarez
Instituto de Física...
Surface Engineering Nanostructures: An Introduction
• Top Down : photo lithographic, micro-contact printing and catalyst g...
Flat panels (CNT-FED) Project CANADIS
Top Down Fabrication: Nanostructured Regular Patterns
Nano-Lithography (Project NANO...
*
Carbon nanotubes grown by CVD
M. Morales,et al., JPhysD., 2013, IFGW-UNICAMP
Top Down Fabrication: Nanostructured Regula...
EDS
EDS
Bottom Up Fabrication: Mesoporous Patterned Silica
Amphiphilic: from the Greek αµφις, amphis: both and φιλíα, phil...
Bottom Up Fabrication: Mesoporous Patterned Silica
J.J.S. Acuña, M.C. Marchi, C. Figueroa, F. Alvarez , Thin Solid Films 5...
Si
Nanotubes growth:Sequential process
Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013
IBD-TINx...
TiNx Buffer Layers Thin Films Preparation
500°C
Sputtering
gun
Turbo
pump
XPS
IBD-TINxOy
H2 Flux 0,1,2,3,4 sccm
Oxygen Con...
Si
Catalyst Ni Particles: Ion Beam
Deposition
Sputtering
gun
Turbo
pump
XPS
Nickel Particles
750°C
1.5 min
deposition
5 mi...
CNTs analysis
6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5
20
40
60
80
100
06121824
[H2]/[N2+Ar], %
NumberofCNTs/µµµµm
2
Oxygen Concent...
CNTs results
O in the film
Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013
CNTs analysis
12
6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5
20
40
60
80
100
06121824
[H2]/[N2+Ar], %
NumberofCNTs/µµµµm
2
Oxygen Conc...
1W. K. Burton, N. Cabrera and F. C. Frank, Royal Soc., 243, 1950; D. Walton in Nucleation, Edited by A. Z. Zettlemoyer, Ma...
Lagally and Zhang, nature, 417, p907, 2002
Thin Films Growth: Surface Phenomenon
Potential Barriers
•Along a Terrace
Cross...
Surface Structuring: Continuation
• Interlayer mass transport: control vertical uniformity
• Controlled by energetic barri...
S. J. Liu et al. Appl. Phys. Lett., Vol. 80, No. 18, 6 May 2002
{111}
{111}
Top View
Diffusing along the terrace
Eb~ 0.45 ...
S. J. Liu et al. Appl. Phys. Lett., Vol. 80, No. 18, 6 May 2002
{111}
{111}
Top View
Instability: Piling up along the terr...
Low energy Ion bombardment nanostructuring Process
Fine control Deposition Parameters
• Ion Species and Ion Energy
• Impin...
Campinas Sky, SP, Brazil
Snow Ripples
Las Leñas, Argentina
Atacama Desert, Chile
Ion Beam Sputtering
Si (110) Xe, 1keV, Pe...
Topography Accident: Sand and Snow
Sand(Snow) Dunes: At the hill or depression, Different Velocities
Clouds: ripples betwe...
Nano-Structures on Gallium Antimonide: Ar+ Ion Sputtering
Facsko et al., Science 285,1999, p1551
Hexagonal Symmetry
4x1017...
Xe+ Patterning: Experiment
Cucatti & Alvarez, PSE 2012
22
•Substrate
•Ion gun
•Turbo
•pump
Material: SS 316, Policrystal (...
Xe+ Patterning
Fixed parameters:
• Room temperature (~25ºC)
• Time: 30 min
• Energy: 1 KeV
• Current density: 0.37 mA/cm²
...
Xe+ Bombardment (SS 316L)
β =15º β = 45º β = 60º
Patterns depend on crystalline orientation
Diffusion regime: time to reac...
SEM-FEG images from AISI 316L using (Xe+, 1 keV)
•25 •PSE 2012 S. Cucatti Sep 12
Crystalline
grains evidenced
Patterns wit...
Xe+ Bombardment SS 316L- Roughness
PSE 2012 S. Cucatti Sep 12
• Competition between the diffusion and
erosive regime ³
• L...
Patterning effect on nitrogen diffusion
New Nitrided Phase
Small Precipitated
Needle Precipitated
Cucatti et al, DFA,IFGW,...
Bombardment Effect
Experimental: Ion Beam
Energy
(nominal): 20 – 1200 eV
PO2 <10-8 mb
Current
(nominal): ~1mA/cm2
TARGET
ION GUN 1
UHV
XPS
SU...
Ion-driven patterning: Bradley & Harper Model
ConvexConcave
M. Bradley and J. M. E. Harper, J. Vac. Sci. Technol. A, 6,4, ...
Ripples Wavelength: Diffusive Regimen
λλλλ=2ππππ (2K/||||vi||||)1/2
i=x,y directions and vi, the largest velocity
Erosion ...
Self-organized 2-D Ni particles deposited on titanium nitride
(a) Near normal substrate ion bombardment
(b) Pattern formed...
Near normal substrate ion bombardment
TiN Deposition: Ion Beam Deposition
Sputtering
gun
Turbo
pump
XPS
Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD...
The original pattern is conserved
Sculpted Si Perpendicularly Xe+ beam TiNxOy coated on sculpted Si
Patterned Si Substrate...
TiN + Ni Particles Ion Beam Deposition
Sputtering
gun
Turbo
pump
XPS
Carbon nanotubes grown by CVD, M. Morales,et al., JPh...
•Self-organized 2-D Ni arrange
•Lattice constant of a x b
2-Fold Symmetry
ππππ
ππππ
+
AFM Image
• Lattice constants: |a|≈171 nm, |b|≈184 nm, 690
• Defects: missing row (“edge dislocations”)
Adatoms: diffusion and coalescence
•The Ni particles diffuse on the surface until incorporated at a nucleation
center.
•Ad...
S. J. Liu et al. Appl. Phys. Lett., Vol. 80, No. 18, 6 May 2002
{111}
{111}
Top View
Instability: Piling up along the terr...
Ehrlich-Shhwoebel (E-S) barrier
λλλλ
Self - Organization
Conclusions
• Process generating organized nanostructures: top down, bottom up and
ion driven
• Different possibilities ge...
Upcoming SlideShare
Loading in …5
×

Engenharia de nanoestruturas de superfície.

2,050 views

Published on

Arquivo do seminário apresentado pelo professor Fernando Alvarez, pesquisador da seção Unicamp do Instituto Nacional de Engenharia de Superfícies, no dia 20 de agosto de 2013, na seção UCS do Instituto, para um público de 30 estudantes e professores de cursos de graduação e pós-graduação.

Published in: Technology, Business
  • Be the first to comment

  • Be the first to like this

Engenharia de nanoestruturas de superfície.

  1. 1. Surface Engineering Nanostructures Low energy Ion bombardment nanostructuring Process Fernando Alvarez Instituto de Física "Gleb Wataghin", Unicamp, 13083-970, Campinas, SP, Brazil Collaborators M. Morales, E. A. Ochoa, S. Cucatti, R. Droppa, R. B. Merlo Equipamentos e ProcessosEquipamentos e Processos
  2. 2. Surface Engineering Nanostructures: An Introduction • Top Down : photo lithographic, micro-contact printing and catalyst growth, masks, writing (electron beam), molds • Bottom Up: Surface Functionalization, Self Organized Nano-Porous Lattice, supramolecular structures (from atomic to mesosopic scales) Self Organization by Ion Beam Treated Surfaces a) Sculpted Substrate By Ion Beam Bombarded b) Self – Organized Structures Obtained By Ion Sputtering • Coclusions
  3. 3. Flat panels (CNT-FED) Project CANADIS Top Down Fabrication: Nanostructured Regular Patterns Nano-Lithography (Project NANOLITH) Cold cathode for hyper-frequency devices (> 30 GHz) Propjet CANVADS Standard Photo-Lithography Electron Beam Patterning Reactive Plasma Etching
  4. 4. * Carbon nanotubes grown by CVD M. Morales,et al., JPhysD., 2013, IFGW-UNICAMP Top Down Fabrication: Nanostructured Regular Patterns Single Carbon nanotubes between triple-layer catalyst (Al~10 nm/Fe~1 nm!/Mo~0.2 nm) Lacerda et al. APL, 84,269, 2004 Single Carbon nanotubes between two electrodes Tans, S., et al., Nature 394, 761–764 (1998).
  5. 5. EDS EDS Bottom Up Fabrication: Mesoporous Patterned Silica Amphiphilic: from the Greek αµφις, amphis: both and φιλíα, philia: friendships, EDS: Energy Dispersive X-ray Spectroscopy Pm3n Cubic Symmetry Cross Section TEM • Mesoporous (Pm3n) films (dip coating) combining polycondensation of silicate species and organization of amphiphilic mesophases • Temperature Evaporation-induced self-assembly of the mesoporous film • Decorated with iron-based nanoparticles in iron aqueous solution (0.2M FeSO4.7H2O) M. C. Marchi, C. Figueroa, and F. Alvarez, J. Nanosc. Nanotechn., 8, 448, 2008 , IFGW, UNICAMP Evaporation-induced self-assembly
  6. 6. Bottom Up Fabrication: Mesoporous Patterned Silica J.J.S. Acuña, M.C. Marchi, C. Figueroa, F. Alvarez , Thin Solid Films 519 (2010) 214–217 • Silica Based Thin Film (Im3m) cubic symmetry • 7 nm cavities sizes separated by ~1.8 nm walls • CVD Carbon Nanotubes Growth TEM-Cross Section SEM-Top View SEM-Top View
  7. 7. Si Nanotubes growth:Sequential process Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013 IBD-TINxOy Nickel Particles CVD-CNTs IBD Si Si + Annealing Barrier layer
  8. 8. TiNx Buffer Layers Thin Films Preparation 500°C Sputtering gun Turbo pump XPS IBD-TINxOy H2 Flux 0,1,2,3,4 sccm Oxygen Containing Control Si Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013
  9. 9. Si Catalyst Ni Particles: Ion Beam Deposition Sputtering gun Turbo pump XPS Nickel Particles 750°C 1.5 min deposition 5 min annealing Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013
  10. 10. CNTs analysis 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 20 40 60 80 100 06121824 [H2]/[N2+Ar], % NumberofCNTs/µµµµm 2 Oxygen Concentration, at.% 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 26 28 30 32 34 36 38 DiameterModeCNTs(nm) Oxygen Concentration, at.% 06 [H2]/[N2+Ar], % 121824 •Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013
  11. 11. CNTs results O in the film Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013
  12. 12. CNTs analysis 12 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 20 40 60 80 100 06121824 [H2]/[N2+Ar], % NumberofCNTs/µµµµm 2 Oxygen Concentration, at.% Oxygen Presence Inhibit Ostwald ripening 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 26 28 30 32 34 36 38 DiameterModeCNTs(nm) Oxygen Concentration, at.% 06 [H2]/[N2+Ar], % 121824 Original Number particles Smaller Si TiNxOy Ni Ni Si TiNxOy Ni Smaller ΦΦΦΦ CNTs More Density CNTs Ostwald ripening
  13. 13. 1W. K. Burton, N. Cabrera and F. C. Frank, Royal Soc., 243, 1950; D. Walton in Nucleation, Edited by A. Z. Zettlemoyer, Marcel Dekker, INC. NY, 1969; W. K. Burton , N. Cabrera. And F. C, Frank, Phil. Trans. Roy Soc., London, A243, 302, 1951 Surface Structuring: a brief introduction • Atoms deposited from the vapor phase • Self-Organizing: Mean Way between kinetic and thermodynamic phenomenon (non-equilibrium) • Surface diffusion on a flat surface (terrace): primary mechanism (activated process) • Mean displacement adatom λλλλ: distance before remains immobilized or detaching to the vapor1 λλλλ=λλλλ0exp [ (εεεεs-us)/2kT] εεεεs : evaporation energies (from the surface to the vapor phase) us : jumping activation energy between two neighboring equilibrium positions distant λλλλ0 each other λλλλ Jumping Detaching F • D/F>>1 Process Governed by Thermodynamic (Near Equilibrium) • D/F<<1 Process Governed by Kinetic D= Diffusion Coefficient
  14. 14. Lagally and Zhang, nature, 417, p907, 2002 Thin Films Growth: Surface Phenomenon Potential Barriers •Along a Terrace Crossing • 3D-Barrier • 2D-Barrier • 1D-Barrier Ehrlich & Schwoebel Barrier
  15. 15. Surface Structuring: Continuation • Interlayer mass transport: control vertical uniformity • Controlled by energetic barriers at the step Ehrlich & Schwoebel Barrier (E-S) : Scale with local coordination Ehrlich &Schwoebel Barrier
  16. 16. S. J. Liu et al. Appl. Phys. Lett., Vol. 80, No. 18, 6 May 2002 {111} {111} Top View Diffusing along the terrace Eb~ 0.45 eV
  17. 17. S. J. Liu et al. Appl. Phys. Lett., Vol. 80, No. 18, 6 May 2002 {111} {111} Top View Instability: Piling up along the terrace Eb~ 0.45 eV
  18. 18. Low energy Ion bombardment nanostructuring Process Fine control Deposition Parameters • Ion Species and Ion Energy • Impinging Angle • Flux (Dose) • Beam Size • Substrate Temperature
  19. 19. Campinas Sky, SP, Brazil Snow Ripples Las Leñas, Argentina Atacama Desert, Chile Ion Beam Sputtering Si (110) Xe, 1keV, Perpendicular Morales, Merlo, Droppa, and Alvarez, 2013. DFA, IFGW, UNICAMP
  20. 20. Topography Accident: Sand and Snow Sand(Snow) Dunes: At the hill or depression, Different Velocities Clouds: ripples between the dry, cool air above and the moist, warm air below Less Velocity Αννννεµος: Wind God
  21. 21. Nano-Structures on Gallium Antimonide: Ar+ Ion Sputtering Facsko et al., Science 285,1999, p1551 Hexagonal Symmetry 4x1017 cm-2, 40 s 2x1018 cm-2, 200 s 4x1018 cm-2, 200 s 500nm 500nm 500nm GaSb Fluences:5.2x1031/nm2;Tempo: 90 min and λλλλ=37–43 nm Au ΘΘΘΘ~730 Dual Ion Beam Sputtering, 2keV
  22. 22. Xe+ Patterning: Experiment Cucatti & Alvarez, PSE 2012 22 •Substrate •Ion gun •Turbo •pump Material: SS 316, Policrystal (austenite) XPS
  23. 23. Xe+ Patterning Fixed parameters: • Room temperature (~25ºC) • Time: 30 min • Energy: 1 KeV • Current density: 0.37 mA/cm² • Power: 0.4W/cm² • Dosis: 2.2 x 1018 • Working pressure: 1.4 x 10-3 mbar •23 •PSE 2012 S. Cucatti Sep 12 Different impinging angles β = 0º, 15º, 30º, 45º, 60º Austenitic Stainless Steel 316L Mirror-polished samples (roughness < 1.5 nm)
  24. 24. Xe+ Bombardment (SS 316L) β =15º β = 45º β = 60º Patterns depend on crystalline orientation Diffusion regime: time to reach equilibrium Cucatti , Morale,Alvarez, DFA, IFGW, UNICAMP, 2013 SEM-FEG
  25. 25. SEM-FEG images from AISI 316L using (Xe+, 1 keV) •25 •PSE 2012 S. Cucatti Sep 12 Crystalline grains evidenced Patterns within the crystalline grains 15º Pattern
  26. 26. Xe+ Bombardment SS 316L- Roughness PSE 2012 S. Cucatti Sep 12 • Competition between the diffusion and erosive regime ³ • Lower angle increasing sputtering • Pattern: direction of the beam Increase of impinging angle 0 15 30 45 60 0 5 10 15 20 25 RMSRoughness(nm) Impinging angle ββββ (degrees) Only polished (<1.5 nm) •[3U.Valbusa, C. Boragno, F. Buatier de Mongeot, J. Phys.: Condens. Matter 14 (2002) 8153-8175
  27. 27. Patterning effect on nitrogen diffusion New Nitrided Phase Small Precipitated Needle Precipitated Cucatti et al, DFA,IFGW,UNICAMP, 2013
  28. 28. Bombardment Effect
  29. 29. Experimental: Ion Beam Energy (nominal): 20 – 1200 eV PO2 <10-8 mb Current (nominal): ~1mA/cm2 TARGET ION GUN 1 UHV XPS SUBSTRATE T Controlled ION GUN 2 TURBO PUMP NG+ Ion gun (Kaufman) Noble gases Bombardment (NG +): Ar +, Kr, + Xe +Noble gases Bombardment (NG +): Ar +, Kr, + Xe + Ar, Xe+
  30. 30. Ion-driven patterning: Bradley & Harper Model ConvexConcave M. Bradley and J. M. E. Harper, J. Vac. Sci. Technol. A, 6,4, 1988 Closer: More Energy in ΘΘΘΘ´ Faster Erosion ΘΘΘΘ´ ΘΘΘΘ
  31. 31. Ripples Wavelength: Diffusive Regimen λλλλ=2ππππ (2K/||||vi||||)1/2 i=x,y directions and vi, the largest velocity Erosion Regimen • Strong Sputtering preventing accommodation by diffusion • The surface nanostructure is forced to following the direction of the ions • Increasing roughness with impinging sputtering angles. • The erosion is mild and diffusion “fast” • The Ripples align along the crystalline direction (thermodynamically equilibrium)
  32. 32. Self-organized 2-D Ni particles deposited on titanium nitride (a) Near normal substrate ion bombardment (b) Pattern formed after bombardment (c) Thin film of TiNxOy on the patterned substrate (d) Self-organized nickel particles deposited on the template M. Morales, R. B. Merlo, R. Droppa Jr, and F. Alvarez, submitted, 2013 , IFGW, UNICAMP Sequential steps in the growing process of the nickel particles self-assembling
  33. 33. Near normal substrate ion bombardment
  34. 34. TiN Deposition: Ion Beam Deposition Sputtering gun Turbo pump XPS Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013 N2
  35. 35. The original pattern is conserved Sculpted Si Perpendicularly Xe+ beam TiNxOy coated on sculpted Si Patterned Si Substrate + Coating
  36. 36. TiN + Ni Particles Ion Beam Deposition Sputtering gun Turbo pump XPS Carbon nanotubes grown by CVD, M. Morales,et al., JPhysD., Submitted, 2013 Si Nickel Particles 750°C 1.5 min deposition 5 min annealing
  37. 37. •Self-organized 2-D Ni arrange •Lattice constant of a x b 2-Fold Symmetry ππππ ππππ +
  38. 38. AFM Image • Lattice constants: |a|≈171 nm, |b|≈184 nm, 690 • Defects: missing row (“edge dislocations”)
  39. 39. Adatoms: diffusion and coalescence •The Ni particles diffuse on the surface until incorporated at a nucleation center. •Adatoms diffuse a mean displacement λλλλ constrained to move on the crest due to the Ehrlich-Shhwoebel barrier, λλλλ= λλλλ0 exp [ (εεεεs-us)/2kT] εεεεs Evaporation energies from the surface to the vapor phase us Jumping energy between two equilibrium positions distant λλλλ0 each other •The adatom diffuses along the top of the hill until meeting a second atom • A particle sink and depleted surrounding neighborhood start.
  40. 40. S. J. Liu et al. Appl. Phys. Lett., Vol. 80, No. 18, 6 May 2002 {111} {111} Top View Instability: Piling up along the terrace Eb~ 0.45 eV
  41. 41. Ehrlich-Shhwoebel (E-S) barrier λλλλ Self - Organization
  42. 42. Conclusions • Process generating organized nanostructures: top down, bottom up and ion driven • Different possibilities generating nanostructures by bombarding • Ion driven patterning can generate regular patterns • Self-organized metallic nano-particles on coated patterned silicon • Self-organization: Irregularities still important (Improving process necessary) • Lack of general theoretical understanding of the general process of self-organization

×