Surface Structure Analysis

inⅠ) Low Energy Ion ScatteringⅡ) Medium Energy Ion Scattering

Simultaneous Determination of Atomic Arrangement

(not only surface atoms but also shallow subsurface atoms)

and Elemental Species of Atoms

by

Specialized form ofIon Scattering Spectroscopy

Ⅰ) Low Energy Ion Scattering

The first idea of Impact Collision Ion Scattering Spectroscopy

(ICISS) 　

Experimental scattering angle θL is taken close to 180°

for quantitative structure analysis

Fig. 1

M. Aono et al., Jpn. J. Appl. Phys. 20 (1981) L829.

Extension of ICISS to more convenientCo-axial ICISS (CAICISS) 　

Experimental scattering angle θL is taken just at 180°

for more convenient quantitative structure analysis

Fig. 2

CAICISS apparatus commercialized by Shimadzu Corp. 　

CAICISS - I

Fig. 4

Fig. 3

CAICISS-I was selected in top-ten Japanese industrial productions in 1991by the Nikkan-kogyoNewspaper.

Power of CAICISS

1) Energy-distribution (spectrum) of scattered ions

2) Angular Dependence of scattered ion intensity

3) Time dependence of spectrum of scattered ions

Time-resolved observation of

dynamic processes

Quantitativeatomic

arrangement analysis

Elemental analysis

of all atoms

Fig. 5

Fig. 6

Fig. 7

22

1

220

22

0

00 sincos

LL M

M

MM

MEE

ab

Method of elemental analysis of surfaces atoms by ion scattering ( in case of CAICISS, θL=180°)

Fig. 8

Time of flight (ns)

Inte

ns

ity

(c

ou

nts

)

F/Ca = 1.0 ±0.2

Composition analysis by CAICISS of a monolayer of CaF2 deposited on Si(111)

Fig. 9

L

a b

Method to determine the shape of shadow cone experimentally by CAICISS

a b

Method to determine the position of atom B relative to the position of atom A by CAICISS

A

B

Inte

nsi

ty o

f io

ns

scat

tere

d f

rom

ato

m B

Fig. 10

Fig. 11

Fig. 12

Structure analysis of TiC(111) surface by CAICISS

Inte

nsi

ty o

f io

ns

scat

tere

d f

rom

Ca

atom

s

Angle

d

0.064±0.005 nm(0.079 nm in bulk)

F

CaSi

(a)

(b)

Structure analysis of CaF/Si(111) by CAICISS

Fig. 13

Structure analysis of Si(111)√3x √3-Ag surface by CAICISS

Fig. 14

Ⅱ) Medium Energy Ion Scattering

Medium-energy CAICISS (ME-CAICISS)

DUOPLASMATRONION SOURCE

X-YSTEERER

EINZEL LENS

ACCELERATIONTUBE

Q-LENS

X-Y STEERER

BENDING MAGNET

COLLIMATOR

CHOPPINGELECTRODE

CHOPPING APERTURE

POSCHENRIEDER ELECTROSTATICDEFLECTOR

MCP

SCATTERED-IONDECELERATION TUBE

SAMPLE

AMPLIFIER CFD

TIME

ANALYZER

PULSEGENERATOR

DELAY

DELAY

(a) Ion beam source in combination with a 100 keV accelerator (b) Beam chopping system

(c) Target on a 3-axis goniometer (d) TOF energy analyzer located at a scattering angle of 180 ゜

(a)

(b)

(c)

(d)

E0 = 100 keV

Subsurface and burried interface structure analysis by ME-CAICISS

Fig. 15

Fig. 16

Sb (δ-doping)

a-Si Si(001)Si

T. Kobayashi et al., Appl. Phys. Lett. 74 (1999) 673

250

200

150

100

50

0

Co

un

ts

520480440400

TOF (ns)

● ■ ▲ ○ □ △

(a)

(b)Sb Si

1.2

1.0

0.8

0.6

0.4

0.2

0.0

No

rma

lize

d y

ield

2520151050

Polar angle (deg)

<001> <017><015>

<014><013>

<012>

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Sb

Si

Fig. 17

(a) (b)

(c)

Co

nce

ntr

atio

n o

f S

b (

%)

302520151050

Depth (nm)

5

4

3

2

1

0

1.0

0.8

0.6

0.4

0.2

0.0

Fra

ctio

n o

f su

bst

itu

tio

nal

Sb

Original position ofδ-doped Sb layer(d)

Annealed at 750 oC

Structure analysis by ME-CAICISS of a Si film with δ-doped Sb (after annealing at 750oC)

25 nm