Henri I. Boudinov Instituto de Física, Universidade Federal do Rio Grande do Sul

1. Ion Beam Analysis Part 1 Henri I. Boudinov Instituto de Física, Universidade Federal do Rio Grande do Sul Porto Alegre, RS, Brazil henry@if.ufrgs.br 26_10_2009 NanoSYD, MCI, SDU, Sønderborg , Denmark

2. Outline • The Porto Alegre Ion Beam Centre • Interaction of ions with matter • Stopping power • Rutherford Backskattering Spectrometry (RBS) • Channeling • Compositional and defect depth profiles • Proton Induced X-ray emission (PIXE) • Nuclear Reaction Analysis (NRA) • Microbeam analysis

3. Porto Alegre Ion Beam Centreestablished in 1981 • Controllable Materials Modification • Facilities • 0.2-3MV Tandetron • 30-500kV Single Ended Implanter • 10-250kV Medium Current Implanter • Implantation 10keV ~15MeV (up to 1mA) • Sample size up to 10cmx10cm • Hot (800oC) or cold (~LN) • Applications • Ion Beam Synthesis • Buried and surface oxides and silicides • Nanocristals • Ion Implantation • Defect Engineering • Proton beam lithography • potentially 1m resolution to 10m depths

4. Porto Alegre Ion Beam Centre • Advanced Materials Analysis • Facilities • 3MV Tandem • Techniques include RBS, MEIS, ERDA, PIXE, NRA • Channelling Spectroscopy for damage analysis • Fully automated collection and analysis • Micro-beam with full scanning • External Beam for vacuum sensitive samples • Applications • Thin Film Depth Profiling • Compositional Analysis • Disorder Profiling of Crystals • 3-D elemental composition and mapping

5. Ion Beam for: • Material Science • Solid State Physics • Atomic and Molecular Physics • Ion Beam Modification of Materials • Ion Beam Analyses • Basic Physics

6. Penetration of the Radiations in Solids • Charged Particles • Electrons: e-, e+, b-, b+ 10m • Ions: p+, He++ (a), etc.. 1m • Uncharged Particles • X-rays and g-rays 10cm • neutrons 10cm

12. Ion Implanter

13. 3MV Tandetron accelerator

15. Penetration of charged particles through matter E. Rutherford, 1911 N.Bohr, 1913-54, 1948 E. Fermi, 1924- H.A. Bethe, 1930- F. Bloch, 1933- L. Landau, 1944- .... Experimental ingredients Ions : Z1=-1,1,2,...~100, electrons, muons, clusters,... energies ~1eV – 1011 eV Target : Z2 = 1,2,.. ~100, solids, gases, liquids, plasma,...

16. Bohr, Bethe,...

17. Stopping Power dE/dx = N.S dE/dx – energy loss [eV/nm] N – atomic density [nm-3] S – stopping power [eV.nm2]

18. dE/dx : two types

19. Low energies vion << ve : the electrons shield (passive) Elastic Collisions The ion lose energy to move the target atoms Nuclear Stopping Power Classic

20. High energies vion ~ ve : active electrons (ionization/excitation, plasmons,...) Inelastic Collisions The ion lose energy to the electrons of the target Electronic Stopping Power Quantum

21. Electronic Energy loss (high energies) Classical theory dE/dx ~Z12 ln (|Z1|) for Z1/v >> 1 Quantum theory dE/dx ~Z12 First-order : for Z1/v <<1

22. Results from Coupled-Channel Calculations proton (b=1) on H(1s)

23. Results from Coupled-Channel Calculations anti-proton (b=1) on H(1s)

25. Transition from electronic to nuclear stopping power

26. Penetration of Ions in Silicon • Energy Loss

28. The Stopping and Range of Ions in Matter Software SRIM

29. Materials Radiation Analysis Concept

30. AES (electron in and out) • RBS, MEIS, LEIS, ISS (ion in and out) • XRF (X-ray, in and out) • XPS (X-ray in, electron out) • SEM/EDS (electron in, X-ray out) • SIMS and ERDA(ion in, target out) • PIXE (ion in, X-Ray out) • PIGE, NRA, ...

31. RBS Energy of recoiling protons give element composition and elemental depth profiles STIM Measure the energy loss of transmitted ions to map density variations 1 – 3 MeV proton beam Sample PIXE Characteristic X-ray emission Simultaneous part-per-million detection of trace elements from Na to U PIGE Nuclear reactions give characteristic gamma rays from light nuclei (e.g. Li, B, F) Ion Beam Analysis (IBA)

33. Energy of ions recoiling from nuclear collisions depends on mass and depth Measure light elements (C,N,O) and thickness or depth profiles MDL around 0.1%, but can be used to help quantify PIXE C O Cl Na Rutherford BackScattering Incident Ion Sample To detector RBS Spectrum of 2mm diameter marine aerosol particle showing sodium and chlorine and carbon and oxygen from the plastic support film

34. Backscattering Spectrometry • Yield • Concentration • Energy • Element (K) • Depth (dE/dx)

36. E1 E0 K = E1 /E0

37. E = E0 – dE/dx(in) x / cos q1 E1 = K E - dE/dx(out) x / cos q2 K E0 - E1 x = K dE/dx(in) / cos q1 + dE/dx(out) / cos q2

39. RBS profiling

40. Fluctuations • number of collisions • impact parameter • charge state • ... 1 Physics 2 3 • roughness • detector parameters • beam spot • .... Dx

41. Multiple scattering Detector aceptance Beam spot Energy straggling

43. monocrystal

46. Thin Film Analysis • Structural information (near surface region) • Increased sensitivity to light impurities

47. Surface Peak RBS MEIS

48. MEIS • Si peaks: • SIMOX better than Si • RTA better than FA As+ 20keV, 5E14 cm-2 + annealing: RTA 1000C/10s or FA 950C/15min

49. Rutherford backscattering spectrometry (RBS) • Nondestructive and multielemental analysis technique • Elemental composition (stoichiometry) without a standard (1-5% accuracy). • Elemental depth profiles with a depth resolution of 5 - 50 nanometers and a maximum depth of 2 - 20 microns. • Surface impurities and impurity distribution in depth (sensitivity up to sub-ppm range). • Elemental areal density and thus thickness (or density) of thin films if the film density (or thickness) is known. • Diffusion depth profiles between interfaces up to a few microns below the surface. • Channeling-RBS is used to determine lattice location of impurities and defect distribution depth profile in single crystalline samples

50. Elastic Recoil Detection Analysis