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

yuriyk@cinvestav.mx

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

1E23

6042105

Ato

ms/

cm3

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

Con

cent

ratio

n, a

tom

s/cm

3

EDX

SIMS

II. “Internal calibration” of SIMS

Elemento Ti* Al* V Mo Zr Fe Si

Concentración, % 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

RS

F, a

tom

s/cm

3

Ip,eV

Zr

Mo

TiV

Al

Si

Fe

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,c

ps

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

nsi

ty, c

ps

Z/q

Ti

V

Cr

MnFe

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

MoTi

2

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/d

C 0.044% n/d 0.050% <15%

N 0.028% n/d 0.062% x2

Na n/d n/d 4E-4% n/d

Al 2.72% 9.2%* 2.72%* n/d

Si 0.12% 0.1% 0.1% <15%

K n/d n/d 3E-6% n/d

Ca n/d n/d 6E-5% n/d

Ti 87.4% 83.2%* 87.4% n/d

V 4.2% 4.5 4.5% <7%

Cr Suma: 0.03%

n/d 0.027% n/d

Mn n/d 0.011% n/d

Fe 0.095 0.1 0.1% <5%

Ni Suma: 0.03%

n/d 0.002% n/d

Cu n/d n/d n/d

Zr 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!