Transcript Slide 1
Ion Beam Analysis Part 1 Henri I. Boudinov Instituto de Física, Universidade Federal do Rio Grande do Sul Porto Alegre, RS, Brazil [email protected] 26_10_2009 NanoSYD, MCI, SDU, Sønderborg , Denmark 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 Porto Alegre Ion Beam Centre established 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 1m resolution to 10m depths 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 Ion Beam for: • •Ion BeamScience Modification of Material •Materials Solid State Physics • Atomic and Molecular Physics • Ion Beam Analyses • Basic Physics Penetration of the Radiations in Solids • Charged Particles • Electrons: e-, e+, b-, b+ • Ions: p+, He++ (a), etc.. • Uncharged Particles • X-rays and g-rays • neutrons 10m 1m 10cm 10cm Ion Implanter 3MV Tandetron accelerator Penetration of charged particles through matter E. Rutherford, 1911 N.Bohr, 1913-54, 1948 E. Fermi, 1924H.A. Bethe, 1930F. Bloch, 1933L. 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,... Bohr, Bethe,... Stopping Power dE/dx = N.S dE/dx – energy loss [eV/nm] N – atomic density [nm-3] S – stopping power [eV.nm2] dE/dx : two types Low energies vion << ve : the electrons shield (passive) Elastic Collisions The ion lose energy to move the target atoms Nuclear Stopping Power Classic 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 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 Results from Coupled-Channel Calculations proton (b=1) on H(1s) Results from Coupled-Channel Calculations anti-proton (b=1) on H(1s) Transition from electronic to nuclear stopping power Penetration of Ions in Silicon • Energy Loss 101 dE/dx (eV/ion/A) E3 100 E1 E2 Target Si (dE/dx) e 10-1 10-2 (dE/dx) n 10-3 10-3 10-2 10-1 100 101 102 103 104 105 E(keV) ion He B As Bi mass 4 11 75 209 E1 E2 E3 0,5 keV 2 keV 0,5 MeV 3 keV 17 keV 3 MeV 73 keV 800 keV 200 MeV 530 keV 6000 keV 2000 MeV The Stopping and Range of Ions in Matter Software SRIM Materials Radiation Analysis Concept •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, ... Ion Beam Analysis (IBA) RBS Energy of recoiling protons give element composition and elemental depth profiles 1 – 3 MeV proton beam STIM Measure the energy loss of transmitted ions to map density variations 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) Rutherford BackScattering • 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 Incident Ion Sample To detector C RBS O Na Cl Spectrum of 2m diameter marine aerosol particle showing sodium and chlorine and carbon and oxygen from the plastic support film Backscattering Spectrometry Yield • Concentration Energy •Element (K) •Depth (dE/dx) K = E1 /E0 E1 E0 E = E0 – dE/dx(in) x / cos 1 x E0 E1 = K E - dE/dx(out) x / cos 2 E 1 2 KE x= E1 K E 0 - E1 K dE/dx(in) / cos 1 + dE/dx(out) / cos 2 RBS profiling 1 2 i. number of collisions ii. impact parameter iii. charge state 3 Dx iv. ... i. roughness ii. detector parameters iii. beam spot iv. .... Physics Fluctuations Energy straggling Multiple scattering Detector aceptance Beam spot 10 8 Counts 6 4 E11 KE00 2 0 0 2 4 6 Energy 8 10 monocrystal Thin Film Analysis 1. Structural information (near surface region) 2. Increased sensitivity to light impurities Surface Peak + + He (1.2 MeV) ® SIMOX H (100keV) + SIMOX 20000 600 random channeling <100> 15000 500 High resolution Counts Counts 400 10000 300 200 5000 100 0 0 240 260 280 Channel RBS 300 320 55 60 65 70 75 keV MEIS 80 85 90 MEIS RTA 1000ºC/10s 2.5 SIMOX Si Si 2.0 O 1.5 Counts 1.0 As 0.5 0.0 FA 950ºC/15min 2.5 SIMOX Si 2.0 1.5 1.0 0.5 0.0 Si peaks:75 80 85 90 Energy (keV) • SIMOX better than Si • RTA better than FA 95 100 As+ 20keV, 5E14 cm-2 + annealing: RTA 1000C/10s or FA 950C/15min 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 Elastic Recoil Detection Analysis Proton Induced X-ray Emission Characteristic X-ray photon Ejected electron • Analogous to EDS using MeV protons • No primary bremsstrahlung, so low detection limits (1-10ppm) • Can be made quantitative K PIXE Ca Fe Cu Zn PIXE Target (Ca) Beam Detector Electronics Counts Ka Kb Energy 1000000 Buffalo River Sediment (NIST 8704) Si 100000 FeKa Al CaKa K CaKbTi Counts/C 10000 Mg TiKb S Na 1000 FeKb Ka Mn Cr ZnKa Cu Ni ZnKb 100 10 PbLa Sr PbLb Rb Ka RbKb 1 0 2 4 6 8 10 Energy (keV) 12 14 16 Applications Microelectronics Environmental sciences Food processing Biological tissues Biotechnology Archaeology - Art Earth Sciences Proton Induced Gamma Ray Emission p • MeV protons can tunnel through the Coulomb barrier of light nuclei to induce gamma emitting nuclear reactions • Gamma energy is characteristic of specific isotopes • Detection limits ~ 0.1 % • Useful for specific problems (e.g. F19, B10/B11) F19(p,ag)O16 19 F Intermediate Ne20 nucleus in excited state Ne20 a Decays to O16 + alpha particle and emits characteristic gamma rays ^3 g O16 f:\pc_users\jpn\971118\490001g4._ : F Tourmaline std: GRR573 F Li Al B10 PIGE Al ^2 Na ^1 Tourmaline standard GRR573 ^0 100 300 500 700 900 1100 1300 1500 1700 Nuclear Reaction Analysis (NRA) p + 18O ®15N + 4He Nuclear Microscopy Beam from Accelerator Lens Sample Detectors Scanning system Map array Y Image in computer memory X • All types of data can be collected simultaneously Scanning Transmission Ion Microscopy Energy High Low STIM • Energy loss of transmitted ions depends on thickness and density. • Use energy loss mapping to image the structure of thin samples (up to 30m). • (No chemical information) STIM image of the leg and claw of a wasp showing internal detail