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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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