fundamentals on surface analysis
TRANSCRIPT
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표면분석입문과정 2009
표면분석개론Fundamentals on Surface Analysis
김정원
나노구조측정센터한국표준과학연구원
(E-mail: [email protected])
May 8, 2019나노계측과학과
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Why are surfaces important?
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환경오염, 미세먼지?
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Definition of Surface
▶ surface ↔ Interface
Outermost layers influencing top layer (2~10 layers)
0.5~ 3 nm (cf. underlying thin film – lubrication, optical properties)
▶ clean surface → interfaces : solid-vacuum (outer space )
solid - liquid
solid – solid
liquid – liquid
▶ Macroscopic surface phenomena
→ adsorption, bonding, catalysis, oxidation, corrosion and other surfacereactions, diffusion, desorption, melting and other phase transformation,
→ etching, crystal growth, nucleation, charge transport (atom, ion andelectron scattering) friction, lubrication, adhesion.
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History of Surface Science
G. Somorjai, Intro. to Surf. Chem. and Catal. (Wiley,1994)
Era of Industrial revolution1823, Pt-catalyzed reaction of H2 and O2
1835, Daguerre process (Ag-coated Cu)1850s, Tribology, Friction1874, Deacon process
1877, Gibbs: Thermodynamics1915, Langmuir adsorption
New era of microscopic investigation1950s, Gas phase molecular process
Petroleum refiningSolid-state electronic devices
1960s, New surface instrumentation & characterization techniques(molecular level studies)
4HCl + O2 → 2Cl2+ 2H2O400oC
CuCl2
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Surface Concentration
G. Somorjai, Intro. to Surf. Chem. and Catal. (Wiley,1994)
Clusters, small particles, and thin films
Dispersion D =No. of surface atoms
Total no. of atoms
Large surface areaLow cost & efficient reaction medium
Link to current nanotechnolgy
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Contents
1. Kinematic theory of gases
2. 표면분석과 (초)고진공시스템
3. 간단한표면분석의원리및응용
4. 각분석법비교
5. KRISS 표면분석인프라소개
1 atm. = 1013 mbar = 1.013 bar = 760 mmHg = 760 Torr = 101,325 Pa (Nm-2)= 14.7 psi = 1.03 kg/cm2 SI unit
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Why is UHV required for surface studies ?
1. To use of low energy electron and ion-based techniques
where : P - pressure [ N m-2 ] k - Boltzmann's constant ( = 1.38 x 10-23 J K-1 ) T - temperature [ K ]– collision cross section π(2r)2
eg) at 10-10 Torr, λ ~ 106 m, 1 atm, λ ~ 60 nm
Inelastic Mean Free Path (IMFP) : λk T
λ = [m]1.414 Pσ
λ = <v>/Z = 1/√2nσ n = N/V = P/kT (number density)
Collision frequency
2r
Average relative speed
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2. To enable atomically clean surfaces contamination-free state during the experiment.▶ Surface concentration:
bulk density : 1g/㎤ ( ice, water )
molecular density :
ρ = 6 ×10 23 × 1/18 = 3 × 1022 molecule/cm3
surface concentration :
σ = ρ2/3 = 1015 molecules/cm2
Why is UHV required for surface studies ?
Maintenance of a Clean Surface P < 10-9 torr
▶ Molecular flux: # of molecules per unit time & area
F = Nsurf/tA = P/√ (2πmkT)
= 1.33×10-4Pa/[2π(18g/6×1023)×1.38×10-23J/K)×298K]1/2
= 8.5×1014 molecules/cm2sec for H2O at RT, 10-6 Torr
≈ 1015
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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
UltraHigh 10-10 3 x 1012 5 x 105 104
Collision Free Conditions P < 10-4 torr
Variation of Parameters with Pressure
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To achieve UHV (초고진공)
Typical procedure1. Proper pumping system: turbomolecular pump with rotary backing,
Ion pump with TSP (Titanium Sublimation Pump)
2. Leak check (ethanol spray or He leak detector)
3. Bake-out for ~20 hours at 150oC
4. Degassing all filaments
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진공펌프 (저진공)
Rotary pump
Dry pump
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진공펌프 (고진공)
Diffusion pump Turbo pump
Ion pump Cryo pump
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Things to be considered in UHV
1. Sealing (Cu Gasket or O-ring)
2. Pressure measurement (gauge)
3. Materials with low outgassing
4. Electrical connections (Ceramic seal tight)
5. Valves
6. Motion (Bellows, magnetic bar)
< Elastomer o-ring vs. Conflat flange(CF) sealing >< Ionization gauge >Baylard-Alpert, hot-cathode
~10-8 ~10-13
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Other pressure gauges
Cold cathode gauge upto 10-9 Torrfree from hot filament, no damage in air rush
Convectron or Pirani Gauge upto 10-3 TorrNonlinear, gas dependentSimilar to thermocouple gauge
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RGA (residual gas analyzer)
- QMS (quadrupole mass spectrometer)
ionizerquadrupole
Faraday cup & multiplier
1. Pressure measurement 10-4 to <10-14 Torr2. Leak detector
After bake-outHydrogen becomes major
High mass signal: oil contamination
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Surface Analysis
PhotonIon
Electron
PhotonIon
Electron
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InputSignal
output Signal
Electron
Ion
Ion Electron
Photon
Photon
AES, EELSLEED, SEMESD
EPMAEDS
INS
XPS, UPS
SIMS, ISS RBS, MEIS
LAMMAPSD, TPD
FTIR, TXRFSERS, XRD
PIXE
XPS : X-ray Photoelectron Spectroscopy
SIMS : Secondary Ion Mass Spectrometry
AES : Auger Electron Spectroscopy
PIXE : Particle induced x-ray emission (경주)
INS : Ion neutralization spectroscopy
Surface Analysis Tools
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표면분석국내현황
◈ 표면분석 기술 교류- 측정클럽 (http://metclub.kriss.re.kr) - 표준연 주관- 표면분석 공동분석 (RRT) - 산업 현장 측정 표준 확립- 표면분석 기술지원 - KBSI, KIST, NNFC, NCNT, DGIST 등
◈ 표면분석 교육- 한국표준과학연구원: 입문자 과정 - 매년 5월 (2일 과정)
전문가 과정 - 매년 9월 (3일 과정)
◈ 표면분석관련 학회 활동- 국내: 표면분석심포지움 (www.kossa2002.or.kr) - 매년 가을
14차 KOSSA: 2019년 9월 25~27일, 제천 청풍리조트- 국외: Practical Surface Analysis (PSA)
3년 주기 한일 공동개최PSA-19: 2019년 11월 4~18일, 일본 삿포로
표면분석교육
표면분석심포지엄
재료측정 국제 워크숍
표면분석 측정클럽
PSA-10
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XPS (150 여대) AES (10 여대)SIMS (70 여대)
ATP (10 여대)
AXIS SUPRA (Kratos)
VersaProbe II (PHI)
ThetaProbe (Thermo Fisher Sci)
IMS-7f (Cameca)
NanoSIMS 50L (Cameca)
TOF.SIMS 5 (ION-TOF)
Scanning Auger Nanoprobe (PHI)
LEAP 4000 HR (Cameca)
국내표면분석장비현황
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전자/X-선과시료원자와의상호작용
X-선, UVElectron
표면탈출: XPS, UPS이차전자증폭발생: SEM
(EDX/WDX)
비탄성충돌: EELS
탄성충돌: XRD, LEED, RHEED
XES (X-ray emission)
(Auger electron)
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Surface Sensitivity
The Inelastic Mean Free Path (IMFP) in metals is typically less than : 10 Angstroms ( 1 nm ) for electron energies in the range 15 < E/eV < 350 20 Angstroms ( 2 nm ) for electron energies in the range 100 < E/eV < 1400
i.e. the IMFP of low energy electrons corresponds to only a few atomic layers.
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P(d) = exp ( - d / )
Electron emission from a sample
IMFP
1.0 2.0 3.0 4.0
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Film Thickness
Chemical StateElement Analysis Atomic Fraction
Elemental MappingDepth Distribution
1000 800 600 400 200 0
Fe 2p
Ni 2p
Binding Energy (eV)
Pure FeFe78-Ni72Fe51-Ni49Fe28-Ni72Pure Ni
108 106 104 102 100 98 96 940.0
5.0k
10.0k
15.0k
20.0k
25.0k
30.0k
Inte
nsi
ty (
cps)
Binding Energy (eV)
0 sec 3 sec 6 sec 9 sec 12 sec 15 sec 20 sec 30 sec 40 sec 50 sec 60 sec 70 sec 80 sec
XPS의응용
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AES
backscattered electron (BSE)
Auger electron secondary electron (SE)
radiative recombination
specimen surface
generation of electron-hole pairs
charge-carrier collection
bremsstrahlung X-rays
inelastically scattered electron
incident electron beam
excitation volume
unscattered electrons
elastically scattered electrons
characteristic X-rays
SEM Image
CL
EBIC
EELS, EFTEM
EDX, WDX
TEM image (DF)
SEM image
+-
EBSD
Diffraction
TEM image (BF) Diffraction
전자빔을이용한표면분석기술
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Scanning Electron Microscopy Tunneling Electron Microscopy
전자현미경
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표면형상 (SEM) 결정구조 (TEM) 조성분포 (SEM, TEM/EDX)
CdTe Film Surface
CdTe Cross Section
CTEM 형상 (BF/DF image)
HR-TEM image 0 100 200 300 400
100
200
300
400
500
600Ge-KSi-K
Inte
nsi
ty
Depth (nm)
Si/Ge 다층박막 단면 분석
CIGS 박막 단면 분석
전자현미경의응용예
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EKLL = EK - ELII – ELIII 입사전자에너지와 무관
Auger Electron Spectroscopy (AES)
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100 nm
0
10
20304050
60708090
100
0 50 100 150 200 250 300Sputter Time (min)
Ato
mic
Co
nce
ntr
atio
n (
%)
O
Al in oxide
Al metal Si
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4-1
0
1
2
3
4
5
x 10
4
Distance (µm)
(P-B
) cn
ts
Al2
Si2
깊이 분포 분석 공간 분포 분석정량 분석
0 200 400 600 800 1000 12002.0M
2.2M
2.4M
2.6M
2.8M
3.0M
3.2M
3.4M
3.6M
3.8M
4.0M
Fe
Fe77.7
Ni22.3
Fe50.6
Ni49.4
Fe27.6
Ni72.4
Ni
10kV 10nA-etch
Inte
nsi
ty (
arb
.un
it)
Kinetic energy (eV)
0 200 400 600 800 1000 1200
Ni
Fe77.7
Ni22.3
Fe50.6
Ni49.4
Fe27.6
Ni72.4
Fe
Inte
nsi
ty (
arb
.un
it)
Kinetic Energy (eV)0 100 200 300 400
0
20
40
60
80
100
16%
84%
Si Ge
Co
mp
osi
tio
n (
%)
Sputtering Depth (nm)
AES의응용예
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이온에너지에따른물질과의상호작용과그의응용
~ eV
~ keV
~100 keV
~ MeV
Ion Beam Deposition
Sputtering (SIMS)Ion Beam Analysis(LEIS)
Ion ImplantationIon Beam Analysis(MEIS)
Ion Beam Analysis(RBS)
DamagedRegion
상온 ~ 26 meV
He Ion Micriscopy (HIM)
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Surface Spectrometry Surface Imaging Depth Profiling
0 1 0 2 0 3 0 4 0 5 0 6 0 7 01 0 0
1 0 1
1 0 2
1 0 3
1 0 4
1 0 5
1 0 6
B
S i
SIM
S In
ten
sity
(cp
s)
S pu tter D epth (nm )
깊이분포도원소 공간 분포원소분석 정량 분석
SIMS의응용예
0 200 400 600 800 1000100
101
102
103
104
105
106
107
10B+
11B+
29Si2
+
28Si2
+
Inte
nsi
ty
Sputter Time (s)
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Evans Analytical Group
Defect analysis in Flat panel display by TOF-SIMS
Polydimethylsiloxane (PDMS) contamination in the stain
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결정성 분석조성 및 깊이분포 분석성분 원소 분석
RBS의응용예
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Technique Comparison
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INS – Inelastic neutron scattering. Bombard a surface with neutrons – energy loss occurs due to the excitation of vibrations. It is most efficient in bonds containing hydrogen.LEED – Low energy electron diffraction. A beam of low energy (tens of eV) electrons bombard asurface; the electrons are diffracted by the surface structure enabling the structure to be deduced.RHEED – Reflection high energy electron diffraction. A high energy beam (keV) of electrons isdirected at a surface at glancing incidence. The angles of electron scattering can be related to thesurface atomic structure.EXAFS – Extended X-ray absorption fine structure. The fine structure of the absorption spectrumresulting from X-ray irradiation of the sample is analysed to obtain information on local chemicaland electronic structure.
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Radiation effects – Surface damage
Damage (penetration depth or momentum transfer, m∆v)photons < electrons < ions
Total damage ~ flux, energy / unit area
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표면분석표준화연구-표면분석용인증표준물질(CRM) 개발
-공동분석을통한표면분석법표준화-국제표준화연구 : ISO-TC 201(Surface Chemical Analysis)
CCQM-SAWG (BIPM - Consultative Committee for Amount ofSubstance)
새로운표면분석법개발-초박막두께측정법 (SiO2, HfO2)
-중에너지이온산란법 (MEIS) : 원자층수준의깊이분해능 (MEIS imaging)-유기바이오표면분석법 (DESI, bio TOF-SIMS)-시분해광전자분광법 (TR-PES, PEEM)
표면분석법의응용연구- CIGS film조성의깊이분포도정량분석- In-situ XPS, UPS분석에의한박막증착기구연구- Bio-SIMS와광전자분광법이용유기물박막및생체조직분석- GCIB를이용한 depth profile방법표준화
Activities at KRISS
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◈ Traceability - CCQM SAWG - traceable to SI unit : m, mol
- by measurement equivalency of NMIs achieved by MRA of NMIs via Key Comparison
◈ International Standard - ISO/TC-201- approved measurement procedure
- practical application of analytical methods
◈ Certified Reference Material (CRM) - NMI- dissemination of traceability- certification by traceable methods
표면분석표준화요소
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BIPM
national body for
standardization - MRA
CGPM
CIPM
CCBIPM
NMIs (NPL, NIST etc)
CIPM
define SI units
establish traceability
10 Consultative Committees
CCL 1952
CCM 1980
CCTF 1956
CCT 1937
CCPR 1933
CCEM 1927
CCQM 1993
CCRI 1958
CCAUV 1998
CCU 1964
CCQM
CMC claim
pilot study, key comparison
KCWG (Key Comparison)
GAWG (Gas Anal.)
EAWG (Electro. Anal.
IAWG (Inorganic Anal.)
OAWG (Organic Anal.)
BAWG (Bio Anal.)
SAWG (Surface Anal.)
7 Working Groups
국제도량형물질량자문위원회
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분과 분과명 국내전문가 ISO 표준 제정 현황제정완료 제정 중
SC1 Terminology 5
SC2 General Procedure 7 4
SC3 Data Management and Treatment 4 1
SC4 Depth Profiling 김경중 6 1
SC5 없어지고 SC7으로 합쳐짐
SC6 Secondary Ion Mass Spectrometry 김경중, 이태걸 9 2
SC7 Electron Spectroscopy 김정원, 김안순 25 3
SC8 Glow Discharge Spectroscopy - 5 1
SC9 Scanning Probe Microscopy 신채호 6 3
SC10 X-Ray Reflectivity 김창수 4+ 3
합계 74+ 18
ISO/TC-201 (from 1991) Surface Chemical Analysis
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Thin film CRMs
Multilayer Thin Film : 5 items
Binary Alloy Thin Film : 3 items
Uniformly Doped Si Thin Film : 2 items
http://eshop.kriss.re.kr/
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시험분석목록
http://eshop.kriss.re.kr/
1. 나노소재평가/표면분석: 스타일러스단차측정, 표면분석시험, SIMS
나노소재평가/표면분석: SEM
2. 나노측정: SPM 측정
3. 신기능재료/표면분석: UPS 측정
4. 첨단측정장비: TEM
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SIMS (CAMECA IMS-7f )
TOF-SIMS IV (ION-TOF)
TEM (FEI, Technai F30)
Facilities at KRISS
XPS (VersaProbe II)
분석이슈가있는의뢰환영 !!
AESAPT