SIMS-EDX system for a standard-free analysis
Yu. Kudriavtsev, R.Asomoza
Sección Electrónica del Estado Solido, Departamento Ingeniería Eléctrica,
CINVESTAV-IPN, Av. IPN #2508, México, DF 07360, México
Introduction
SIMS as any other technique has advantage as well as weak points. The most important disadvantage is poor quantification of SIMS data: by using implanted standards quantification can be done with an experimental error of around ±20%. SIMS analysis of main elements (the concentration range of 1%-100%) cannot be quantified by SIMS using implanted standards; a special calibration procedure should be performed, because of non-linear dependence between concentration of the element of interest and experimental secondary ion current, monitored for it.Energy dispersive X-ray spectroscopy ideally complements SIMS, because of standard free quantitative analysis of most of the elements with the concentration from 0.01 atomic % to 100 atomic %.
General idea:
Utilize an Electron Gun of any SIMS instrument, used typically for charge compensation, to excite characteristic X-Ray emission from analyzed sample to realize Energy Dispersive X-ray spectroscopy method with the SIMS instrument.
Installation of EDD at ims-6f instrument
Si crystal of EDD
Primary ion trap
EDX detector:Exterior view
A modified Strip: the closed window protect EDD in the SIMS mode
Application of EDX-SIMS instrument:
I. Semiconductors1.Quantitative analysis of solid solutions: bulk, thick films, thin films. See Poster Section: Tue-pos-432. Calibration of SIMS (RSFs) for main element analysis in complex materials.3. Shallow junction analysis (LEXES “inside“). II. Metals and alloys:Quantitative analysis of bulk, thick films and thin films.
III. Glass (including natural), ceramics, minerals, etc.Quantitative analysis of bulk, thick films and thin films.
X-ray spectrum of obsidian
Two different strategies:
I. Perform a quantification of main elements by EDX ,
then analyze dopants and contamination by SIMS
0 200 400 600 8001E18
1E19
1E20
1E21
1E22
1E236042105
Atom
s/cm
3
Time, sec
133Cs14N 133Cs16O 133Cs24Mg 133Cs27Al 133Cs69Ga 133Cs21H
MBE grown 1 micron epi-layer of Al0.2Ga0.8N: EDX spectrum and SIMS depth profile
1E14
1E15
1E16
1E17
1E18
1E19
1E20
1E21
1E22
1E23
Conc
entra
tion,
ato
ms/c
m3
EDX
SIMS
II. “Internal calibration” of SIMS
Elemento Ti* Al* V Mo Zr Fe SiConcentración, % atómicos
83.2 9.2 4.5 3.0 0.1 0.1 0.1
5 6 7 8 9 101E21
1E22
1E23
1E24
1E25
RSF,
ato
ms/c
m3
Ip,eV
Zr Mo
TiVAl
SiFe
Fig. RSFs as a function of Ionization potential of element. Points show experimental RSFs, found by SIMS with using of EDX data.
EDX spectrum and found composition of Ti allow
Fragments of mass- spectrum, acquired by SIMS for Ti allow
4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36100
101
102
103
104
105
106
107
In
tens
ity,cp
s
Z/q
C
O
NO++
B
Na
Al
Si O2
Ti++
30 40 50 60 70 80 90100
101
102
103
104
105
106
107
Inte
nsity
, cps
Z/q
Ti
V
CrMn
Fe
Ni
TiO
TiO2
KCa
Se
80 90 100 110 120 130 140 150 160100
101
102
103
104
105
106
107
Inte
nsity
, cps
Z/q
MoTi2
Zr Ti2O
TiMo
Cs
MoOIn
170 180 190 200 210 220100
101
102
103
104
105
106
107
Inte
nsity
, cps
Z/q
Elemento
Certificate
EDX SIMS Falla, %
H 0.072% n/d 0.091% <26%B n/d n/d 3E-4% n/dC 0.044% n/d 0.050% <15%N 0.028% n/d 0.062% x2Na n/d n/d 4E-4% n/dAl 2.72% 9.2%* 2.72%* n/dSi 0.12% 0.1% 0.1% <15%K n/d n/d 3E-6% n/dCa n/d n/d 6E-5% n/dTi 87.4% 83.2%* 87.4% n/dV 4.2% 4.5 4.5% <7%Cr Suma:
0.03%n/d 0.027% n/d
Mn n/d 0.011% n/dFe 0.095 0.1 0.1% <5%Ni Suma:
0.03%n/d 0.002% n/d
Cu n/d n/d n/dZr 0.058 n/d 0.06% <4%Mo 2.7% 3.0% 3.0% <10%In n/d n/d 1.4E-4% n/d
Table 1 Composition of Ti allow, defined by EDX/SIMS in comparison with Certificate of the provider.
* Rose rows corresponds to elements used for SIMS calibration.
Conclusions:
1.EDX technique ideally complements SIMS for a
quantitative analysis of complex materials.
2.Any SIMS instrument, equipped by an Electron Gun,
can be “modified” to perform EDX analysis.
3.Energy of primary electron beam can be varied from
0 to 10keV, this means we can vary thickness of the
analyzed layer from several microns down to a hundred
nanometers.
4.Standard-free analysis in the “full” range of
concentration: from 100 atomic % down to 10-7 atomic
%, can be realized with a reasonable accuracy.
THANK YOU FOR YOUR ATTENTION!
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