Auger Electron Spectroscopy, AES...歐傑電子能譜儀 (Auger Electron Spectroscopy, AES) An Auger...
Transcript of Auger Electron Spectroscopy, AES...歐傑電子能譜儀 (Auger Electron Spectroscopy, AES) An Auger...
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歐 傑 電 子 能 譜 儀
化 學 分 析 電 子 儀
Electron Spectroscopy for Chemical Analysis, ESCA
Auger Electron Spectroscopy, AES
材料系 徐雍鎣
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當原子內層電子受激游離,產生一電洞,上層電子會填補此一電洞以降低原子之位能,此
一降低的能量若大於同層或上層能階某電子的束縛能時,該電子將有機會被游離出原子,
經此過程被游離的電子依發現者(Pierre Auger)的姓氏命名為Auger電子。
The kinetic energy of the Auger electron (XYZ)
is
Ek(XYZ) = Ex - Ey - Ez
where Ex, Ey and Ez are respective binding
energies for electrons in level X, Y and Z.真空態
E xyz= EX -EY -EZ
歐傑電子動能
自由原子
EZ
X
Z
Y
EY
EX
歐傑電子
游離電子
激發探束No Auger transition can be observed for hydrogen
and helium because 3 electrons are required to
complete the Auger transition process .
歐傑電子能譜儀 (Auger Electron Spectroscopy, AES)
An Auger transition can be expressed as the
following general form, XpYqZr, where X, Y and Z
are principle levels, and subscripts, p, q and r, are
subshells of X, Y and Z, respectively
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L2,3
3p
2p
Vacuum level
3s
2sL1
M2,3
M1
3d/4s/4p
Free atom
K 1s
29Cu
14Si
KLL
原子序越大, 外層電子越多, 束縛能越大 !
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For a solid sample, EB = hν - KE - φ;
φ: 試品功函數(Work function)
φ
電子能量分析器電子束
試片電子訊號
X-ray
一般AES分析係利用一電子束(2 - 30 KeV)照射在試品表面上以激發帶特性動能的Auger電
子,經由Auger電子的動能,試驗者可判斷試片表面的元素成份或化學態。
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Electrons emitting form
an Ag surface irradiated
with an electron beam of
1 keV.
Auger electrons
Elastic peak
Plasma lossSecondary electrons
Au
ger
inte
nsit
y (
cn
ts/s
ec)
Au
ger In
ten
sity
(dI/d
E)
Kinetic Energy (eV)
AES spectrum of Si(100);
differential spectrum (above) and
integrated spectrum.
一次電子
背向散射電子
穿透電子
X光 二次電子
Auger電子
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MNN
LMMTriplet
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AES spectra of the first row of transition metals
第 一 列 過 渡 金 屬 A E S 能 譜
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992
842 850
862
942
801734 770778
721
66
11048
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Si3N4
SiO2
Si
Si(LMM) Si(KLL)
Chemical State Analysis by AES
Differential spectrum
Differential spectrum
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AES Analyses of Diamond,
Graphite and a-carbon
200 225 250 275d
N(E
)/d
E
Electron Energy (eV)
a-Carbon
Graphite
Diamond
235 245
256
268
Ao
(KV1V1)A1
(KV2V3)
Ao-wsAo-wp
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500 1000 1500 2000
C(KLL)
Fe(LMM)
Kinetic Energy (ev)
SURVEY AES
Catalyst: Fe,
Gas source: CH4/H2,
Growth by MPCVD
SEM image of the capping
layer on Fe nanoparticles
Carbon capping layer analysis for iron nanoparticles by AES
AES survey spectrum
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500 1000 1500 2000
C
Fe
Kinetic Energy (ev)
SURVEY CNPs(Fe)
200 220 240 260 280
E d
N(E
)/dE
Kinetic Energy(ev)
CNPs(Fe)-C
Damond
Graphite
crystal
Poly-
Graphite
a-Carbon
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1. Ultra-high Vacuum system
2. Electron gun
3. Electron energy analyzer
4. Detection system
5. Data acquisition system
歐 傑 電 子 儀 系 統 示 意 圖
電子訊號
電子能量分析器
電子槍
試片
二次電子檢測器
Ultra-high Vacuum
E1Eo
E2
ExcitationSource
Sample
Signal
TransferLens
R1
R2
Ro
(V1)
Vo
(V2)
Hemispherical analyzer (HSA)
(球扇電子能量分析器)
電 子 能 量 分 析 器
V2 - V1 = Vo [(R2/R1) - (R1/R2)]
Vo = K(V2 –V1)
K is called the spectrometer constant.
Feaures of HSA
* Low transmission without a transfer lens.* High energy resolution.
DE / E = Constant
DE : Energy resolution
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X-ray or e-beam radiation
Sample
E-gun DeflectedElectrons
SignalR1
R2
V
a
E = [Ke V/ ln(R2/R1) ]
E = K’eV
Features of CMA:* high transmission* relatively low energy resolution* sensitive to sample position
Cylindrical mirror analyzer (CMA)
(筒鏡電子能量分析器)
電 子 能 量 分 析 器
K’ is again the spectrometer constant.
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Analysis Methods using AES
由於低能電子(1 - 3 KeV)在固態材料之平均自由行徑(Inelastic mean free path)很短(5 Å - 20
Å ),AES檢測的深度大致上在50 Å 以內;當電子束直徑很小時,SAM技術可得取SEM
及表面元素之Auger影像,如果利用離子束濺射試樣表面,並檢測產生之新表面的Auger
訊號,便可得到試樣自表面到內部的元素成份縱深分佈(Depth Profiling),因此適合分析
薄膜及披覆材料。
Mapping
E-beam
Survey scan
E-beam
dN
/dE
E(eV)
Depth profiling
Ion beamE-beam
Depth (nm)
At.
Co
nc.
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Aluminum oxide defect on poly-Si
SEM image of the bridge defect
on poly-Si gate pattern
The Al(KLL) Auger map (green)
overlapped on the SEM image.
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Red: N, Green Al, Blue: Si
Submicron defect analysis by Auger electron microscope
Source : PHI
The top of the dot off the patterned oxynitride
feature is Al according to Auger analysis.
A dot (0.25 mm)was found after
the deposition of the blanket
silicon oxynitride film and after
the plasma etch of the film.
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縱深成份分佈分析 (Depth Profiling)
Surface Analysis techniques can be used to study the atomic composition as a function of
depth from the surface of solid materials. This technique is called depth profiling. For
destructive depth profiling, an ion beam is used to erode the sample surface. The newly
created surface after ion sputtering is then analyzed with AES or ESCA. Thus, atomic
compositions at various depths below the sample surface can be derived from the
successive sputtering and measurement cycles.
原子濃度
縱深 (濺蝕深度)
A
B
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能量分析器(AES, ESCA)
1
離子束
電子束
1 2 3
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AES depth profiles for Ni(50 nm)/Cr(50 nm) multilayer.
(a) static sample, (b) rotating sample.
NiCr
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AES depth profiles for the interface between
TaSix and Poly-Si films.
?TaSix
Si
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Thin gate oxidation with N2O
Si SiOxNy
SiO2
Raw data
Depth
profiles
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K
ML
N XPS (X-ray Photoelectron Spectroscopy)
X光光電子儀
X光XPS光電子
UPS光電子
UV光
Ek = hn - EB EB = hn - Ek
where h: Planck constant, n: the photon frequency, and
EB : the binding energy of the photoelectron.
UPS (Ultra-violet photoelectron spectroscopy)
UV光光電子儀
For a solid sample, EB = hν - KE - φ;
φ: 試品功函數(Work function)
φ
化 學 分 析 電 子 儀
ESCA (Electron Spectroscopy for Chemical Analysis)
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球扇形能量分析器
檢測器
數具擷取系統
Ultra-high Vacuum
X光光源
表面~5 nm
X-光
光電子
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Light source for Photoelectron spectroscopy
1. Core Level Excitation
2. Deacceleration of Electrons
(Bremsstrahlung)
X-r
ay
In
ten
sity
Filter Cutoff
Energy
Ka
Flux distribution
of a typical x-ray source
電子束
X光
Al 窗
Twin-Anode X-ray Source
HV
冷卻水陽極
燈絲
X-ray photoelectron excitation source
Y Mz 132.3 0.44
Zr Mz 151.4 0.77
Na Ka 1041.4 0.4
Mg Ka 1253.6 0.7
Al Ka 1486.6 0.8
Si Ka 1739.4 0.8
Ti Ka1 4511 1.4
Cr Ka1 5415 2.1
Cu Ka1 8048 2.5
Radiation Energy (eV) FWHM (eV)
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Chemical Structure Study by ESCA
BE(i) ~ Ei + qki
Ei : 元素(q=0)電子i 之束縛能。
k: 常數, q: 原子上的電荷。
Ethyl trifluoroacetate
F adsorbs on Si surface
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Oxidation of the Si(100) surface studied by XPS with synchrotron radition (120 eV)
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Auger
O(KLL)
C(KLL)
Silicon
plasmon
X-raysatellite
ESCA 能譜上的各種訊號峰
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13.2 eV
Doublet peaksSpin - Orbital angular momentum
coupling induced energy splitting
Atomic energy level diagram
1s
2s
2p
3s
3p
3dM Shell
L Shell
K Shell
ORBITALS
EN
ER
GY
4s
4p
4d
4f
N Shell
1/2
1/2
1/23/2
1/2
1/23/2
3/25/2
j STATES
1/2
1/23/2
3/25/2
5/27/2
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Scanning Auger Nanoprobe (AES)
工程六館材料系 Room FE215
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Turbo pump
Rotary pump
E-gun
Ion gun
SEM detector
Energy analyzer
Sample
Manipulator
Ion pump
Load -lock
Sample carrousel
試片轉盤
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析服務時段。
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服 務 辦 法
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