Nanometre scale chemical mapping of organic and inorganic
materials using secondary ion mass spectrometry (SIMS) and
focused ion beam SIMS (FIB-SIMS)
David McPhail
david.mcphail@utdallas.edu
Nanometre scale chemical mapping of materials
nanoSIMS
IMS 5F
TOF SIMS
Microprobe
What role if any do minor and trace elements play in giving spiders silk its unique properties ?
Nanometre scale chemical mapping of materials
Contents of my talk
Introduction to Mass Spectrometry
Introduction to SIMS technique
Examples of what SIMS might be able to do for you
Semiconductors – dopant distributions
Micrometeorites
Worms – gut chemistry
Spider silk
Cultural heritage
Includes examples of complimentary techniques / multi – modal
imaging / image registration from different techniques (FIB)
Mass Spectrometry
F=qE
F=Bqv
Mass Spectrometry
F=Bqv
R = c (m/q)
Isotopes
A Mass Spectrum
Intens, c/s
1e6
1e4
1e2
1e0
20
40
60
Mass, a.m.u.
80
100
Mass spectrometers measure the mass to charge ratio
The SIMS Process
The SIMS Process
Primary Ion
Secondary Ion
Shrapnel !
Vacuum
Solid
Collision
Cascade
Sputtering
Depth
Primary Ion
Penetration Depth
Implanted Ion
For O+ ions in silicon R = 2.25 E (cos) ......nm
ION TOF TOF SIMS/LEIS
depth profiling dr<1nm
imaging~200nm
ZYGO Newview Interferometer
Topographic
mapping ~1nm dr
Air based !
FEI FIB 200 SIMS
FIB milling and
imaging ~5nm
Millbrook miniSIMS
Static SIMS
Portability
Student friendly
The SIMS Equation
Transmission T
SIO MS
detector
neutrals
Primary
ions Ip
Is secondary
ions
concentration 
A
z = depth increment
Is = ( A z ) (  T ) (  ) ions
I s = V Y 
Is
SIMS Modes of operation
Mass spectrometry
All elements and isotopes
Symbol
Adjacent Average: 10
Substance
Sample:
Comment:
CsNa
CsMg
Depth profiling
Origin:
File:
Polarity:
CsCa
CsSiO
Composition / weight%
Distribution of elements with depth resolved to
0.3nm
CsK
10
2
10
1
10
0
Cs2 H
Venetian Glass
--Imperial Co
RX02129B.TFD
positive
Analysis Parameters:
PI:
Energy:
Current:
Area:
PI DD:
Bi 3+
25 keV
0.40 pA
99.6x99.6 µm²
4.34E+013 Ions/cm²
Sputter Parameters:
SpI:
Cs +
Energy:
1 keV
Current:
138.00 nA
Area:
300.0x300.0 µm²
Sp DD:
1.65E+018 Ions/cm²
O 2 flooding:
tascon GmbH · Münster, Germany
200
400
600
Depth/nm
Field of View: 284 x 284 µm2
Imaging
Polymer (PP)
Lateral distribution of elements (100nm easy
and 5nm with FIB)
Melt Stabiliser
Antioxidant
Polymer, Stabiliser, Antioxidant
Surface analysis
All you need to know in one slide
Probe
Information
E = efficiency
Sample
Analytical environment
=excitation process
The need for vacuum in surface analysis
• To avoid contamination as the analysis proceeds !
• To have a long mean free path for ions and electrons
• Samples that outgas are problematic (bio)
Degree of
Vacuum
Pressure
(Torr)
Gas Density
(molecules m-3)
Mean Free
Path (m)
Time/ ML
(s)
Atmospheric
760
2 x 1025
7 x 10-8
10-9
Low
1
3 x 1022
5 x 10-5
10-6
Medium
10-3
3 x 1019
5 x 10-2
10-3
High
10-6
3 x 1016
50
1
Ultra-High
10-10
3 x 1012
5 x 105
104
nb 1 mbar = 0.75 Torr See Martin Knudsen - Kinetic theory of gases
Nanotechnology and nano-volume analysis
Impurity analysis
Box width
Number of
atoms
10µm box
10nm box
ppt
ppm
ppb
~ 1014 atoms 1011
108
105
~ 105 atoms
0.1
0.0001
102
•Need to analyse lots of 10nm box to get ppm analyses
Nanoscale analysis
of materials using
SIMS
Case Study 1
Dopant Distributions in Semiconductors
© Imperial College London
Dopants in Semiconductors
Scan
1000umx1000umx10nm
A SIMS depth profile of a low-dose potassium implant into silicon showing a dynamic
range of over six orders of magnitude and a discernible profile shape down to a
concentration of 10 parts per trillion of potassium in silicon. The data was taken on a
Cameca IMS 6F using an oxygen primary ion beam
Dopants in Semiconductors
Thermal Oxynitrides with
Different Process Conditions
1E+23
S1
S2
1E+22
S3
S4
1E+21
S5
S6
1E+20
1E+19
0
2
depth [nm]
4
6
Ultra-shallow SIMS depth profiles of the nitrogen concentration as a function of
depth for six oxy-nitride films that were subject to different processing conditions.
The samples were analysed using a 250eV oxygen beam at an angle of incidence
of 70o on an Atomika 4550 at FEI Munich
Semiconductor multilayers
Inter-laboratory comparison - Sarah Fearn and Nikolai Yakovlev / Debbie Seng
1000000
BaTiO3
30nm LaSrMnO3
SrTiO3
O
O
100000
Na
Na
10000
Intensity
Ti
Ti
1000
Mn
Mn
100
Sr
Sr
10
Ba
Ba
1
0
200
400
Time (s)
600
800
La
La
Cs Depth Profiling: Solid Lines – IMRE ----- Dotted Lines -IC
Nanoscale analysis
of materials using
SIMS
Case Study 2 Micrometeorites (space junk)
FIB SIMS Analysis of Micrometeorite Impact Site
FIB mill lip
of crater
FIB
SIMS
Gold Film on Nickel
substrate - retrieved
from the International
Space Station
SIMS of Crushed Aerogel Keystone (MIR)
Aerogel
5-100
kg/m3
Orbital
debris
collector
Optical
Original surface
Na+
Mg+
Al+
Cr+
Bi+ at 25keV, 0.2pA
Scanned area 500um x 500um
Nanoscale analysis
of materials using
SIMS
Case Study 3
Biomaterials and soft tissues (worms)
© Imperial College London
SIMS analysis of the location of a gut metabolite in an earthworm
Polyphenols are produced by plants to protect them again animals (herbivory)
Research question: how do worms protect themselves against polyphenols in their diet which
would otherwise attack their gut enzymes ?
Strategy: Survey mass spectra for possible compounds (metabolites) that will offer resistance
to the polyphenols. Once candidate compounds ae determined find where they are in the worm
using SIMS imaging of a lateral section and cross –sections.
Sample prep: Adult L. rubellus. Worms frozen and then subject to cryo-sectioning. 15um
sections extracted with frozen scalpel, thaw mounted on slides and dried in a dessicator.
Main finding: Earthworms possess a class of unique surface-active metabolites in their gut,
which we term ‘drilo-defensins’ at mass 259.1004 and identified from fragmentation patterns as
(2-hexyl-5-ethyl-furan-3-sulfonate). These compounds counteract the inhibitory effects of
polyphenols on earthworm gut enzymes by acting as surfactants.
Unique metabolites protect earthworms against plant polyphenols, Nature communications 6, Article 7869, August 2015, Liebeke et al, DOI:
10.1038/ncomms8869
SIMS analysis of the location of a gut metabolite in an earthworm
1mm
Upper image:
5mm
Drilodefensin (compound 1) distribution
in an earthworm, schematic multi-modal
three-dimensional model based on
micro-computed tomography integrated
with IMS data
TOF-SIMS analysis of a longitudinal crosssection through middle plane of earthworm,
compound 1 in orange (m/z 259 Da)
Lower image:
Optical light-microscopic image
Nanoscale analysis
of materials using
SIMS
Case Study 4
Elemental analysis in spider silk
© Imperial College London
Analysis of Spider Silk
Analysis of Spider Silk
SIMS images of the elements in the silk
16O
19F
26CN
37Cl
51KC
SE
31P
35NaC
Analysis of Spider Silk
Si
P
K
Silk
Silicon substrate
Nanoscale analysis
of materials using
SIMS
Case Study 5
Ultra-Slow Corrosion in Glass - kinetics
The Corrosion of Museum Vessel Glass
“There is nothing inherent in the
glassy state that implies stability”
A 17th/18th century Venetian
goblet
The Corrosion of Museum Vessel Glass
A typical SIMS depth profile of glass RG1 aged at 55%RH and room temperature for
96 hours. A linear scale is used for the secondary ion intensities, and the depth scale
has been calibrated by assuming a uniform sputter rate throughout the analysis.
The Corrosion of Museum Vessel Glass
The Na profiles for samples aged at 55%RH and room temperature for 48, 72, and 96
hours, compared to the un-aged glass. Inset: Schematic showing the area
representing the leached sodium atoms on the SIMS concentration-depth
The SIMS Process
What atoms are in my sample ?
All elements and isotopes
z
Where are they (resolution)?
Resolution 0.3nm in depth (z)
5nm laterally in x and y
How many atoms are there (sensitivity) ?
Sensitivity of ppb in favourable cases (can measure a local
concentration of 5x1013 atoms/cm3 in silicon)
Is the distribution of atoms changing with time, and how
(mechanisms and kinetics) ?
~1nm per day ~ 0.4µm per year ~ 0.4mm per millenium
Extra slides
Extra slides
Extra slides
Nanoscale analysis
of materials using
SIMS
Case Study
Oxidation and crack tip development in
aerospace alloys
The most familiar component
is the high pressure turbine
blade – a single crystal nickel
superalloy with complex
internal cooling and a ceramic
thermal barrier coating to keep
it operating in environments
up to 400oC higher than its
melting point.
Trent 800
Now up to
1600oC in
Trent 900
and Trent
XWB
© Imperial College
engine (Roll s-RoycePage
Trent40800), showing the diff erent stages:
London
http://www.rolls-royce.com/about/technology/material_tech/high_temperature_materials.jsp
mediate pressure compressor (IPC), high
pressure compressor
Crack propagation mechanisms in a high temperature
oxidising environment
FIB-SIMS elemental maps of oxygen distributions around a
fatigue crack prep
(a) 16O-
(b) 18O-
Complimentary FIB-SEM FIB-SIM and TOF SIMS Images
FIB-SEM
FIB SIM
FIB SIM INVERSE
TOF SIMS O 16
TOF SIMS O18
TOF SIMS O18
TOF SIMS O 16
TOF SIMS O18
TOF SIMS O18
Nanoscale analysis
of materials using
SIMS
Case Study
Microsphere Analysis
© Imperial College London
Focussed Ion Beam Milling of Silica Microspheres
Nanopatterning via Near Field Focussing by Microspheres
Apertures fabricated on a 2D lattice
of SiO2 microspheres (d = 4 µm)
covered with 75 nm Au by singlepulse Ti:Sapphire-laser irradiation (
 800 nm,   120 fs) [after Langer
et al. 2005].
YBa2Cu3O7- film on (100) MgO
patterned by means of 248 nm KrF
laser radiation (  24 ns) and a
2D lattice of a-SiO2 microspheres
(d = 1.5 µm) [after Brodoceanu et
al. 2005].
From Professor Dieter Bauerle,
Johannes Kepler University, Linz, Austria
Imperfect optical quality will compromise near field foc
Focussed Ion Beam Milling of Silica Microspheres
Results - Fusokk silica microsphere
“Imaging porous insulating materials – analysis of silica
based bone scaffolds”
Strategies for the chemical analysis of highly porous bone scaffolds using secondary ion mass
spectrometry, Daming Wang et al, Biomedical Materials, 9 (1), doi:10.1088/17486041/9/1/015013
How can we analyses samples that are rough,
porous and insulating ?
100.00 μm
100.00 μm
7.0
100.00 μm
100
6.0
1600
5.0
80
1200
4.0
60
3.0
800
40
2.0
400
20
1.0
0
total
MC: 1932; TC: 3.724e+008
Ca++
MC: 7; TC: 1.577e+004
0.0
Si+
MC: 113; TC: 3.950e+006
0
Defining and studying surfaces
The SIMS Group
What atoms are in my sample, where are
they and at what concentration ?
Hierarchical Analysis Strategy
(with fiducial registration)
From non destructive air based techniques to destructive
vacuum based techniques
Optical microscopy
White light interferometry
AFM
SEM-EDX
SIMS
Channeling contrast
FIB SEM images of a micrometeoroid previously milled to create a ‘double-cross
section’. The images are taken with the sample stage rotated to 35 and 50 degrees
respectively and the channeling contrast clearly reveals the grain structure. Sample
from the solar array on Hubble