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1 歐傑電子能譜儀 Auger Electron Spectroscopy, AES 化學分析電子儀 Electron Spectroscopy for Chemical Analysis, ESCA 材料系徐雍鎣 1

2 歐傑電子能譜儀 (Auger Electron Spectroscopy, AES) 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 電子歐傑電子動能 The kinetic energy of the Auger electron (XYZ) is E k (XYZ) = E x - E y - E z 歐傑電子 E xyz = E X -E Y -E Z 真空態 where E x, E y and E z are respective binding energies for electrons in level X, Y and Z. 激發探束 E Z Z Y E Y E X No Auger transition can be observed for hydrogen and helium because 3 electrons are required to complete the Auger transition process. 游離電子自由原子 X 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 2

3 M 2,3 M 1 L 2,3 L 1 Vacuum level KLL 3d/4s/4p 3p 3s 2p 2s K Free atom 1s 14 Si 29 Cu 原子序越大, 外層電子越多, 束縛能越大! 3

4 X-ray 電子束電子能量分析器試片電子訊號 For a solid sample, E B = hν - KE - φ; φ: 試品功函數 (Work function) φ 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 4

5 Auger intensity (cnts/sec) Auger Intensity (di/de) AES spectrum of Si(100); differential spectrum (above) and integrated spectrum. Electrons emitting form an Ag surface irradiated with an electron beam of 1 kev. Kinetic Energy (ev) 一次電子 Elastic peak 背向散射電子 X 光 Auger 電子二次電子 Auger electrons 穿透電子 Secondary electrons Plasma loss 5

6 MNN LMM Triplet 6

7 AES spectra of the first row of transition metals 第一列過渡金屬 A E S 能譜 7

9 Differential spectrum Chemical State Analysis by AES Si(LMM) Si(KLL) Differential spectrum Si SiO 2 Si 3 N 4 9

10 dn(e)/de AES Analyses of Diamond, Graphite and a-carbon 256 A 1 (KV 2 V 3 ) A o (KV 1 V 1 ) A o - w p A o - w s Diamond Graphite a-carbon Electron Energy (ev) 10

spectrum SURVEY AES Fe(LMM) Catalyst: Fe, Gas source: CH 4 /H

11 Carbon capping layer analysis for iron nanoparticles by AES SEM image of the capping layer on Fe nanoparticles AES survey spectrum SURVEY AES Fe(LMM) Catalyst: Fe, Gas source: CH 4 /H 2, Growth by MPCVD C(KLL) Kinetic Energy (ev) 11

12 E dn(e)/de SURVEY CNPs(Fe) Fe Damond C Kinetic Energy (ev) Graphite crystal Poly- Graphite CNPs(Fe)-C a-carbon Kinetic Energy(ev) 12

13 歐傑電子儀系統示意圖 Ultra-high Vacuum 1. Ultra-high Vacuum system 2. Electron gun 3. Electron energy analyzer 4. Detection system 5. Data acquisition system 二次電子檢測器電子槍電子能量分析器試片電子訊號 13

14 Hemispherical analyzer (HSA) ( 球扇電子能量分析器 ) 電子能量分析器 Ro E1 Eo E 2 R2 (V2) Transfer Lens V o R1 (V1) Signal V 2 - V 1 = Vo [(R 2 /R 1 ) - (R 1 /R 2 )] V o = K(V 2 V 1 ) K is called the spectrometer constant. DE / E = Constant DE : Energy resolution Excitation Source Sample Feaures of HSA * Low transmission without a transfer lens. * High energy resolution.

15 電子能量分析器 Cylindrical mirror analyzer (CMA) ( 筒鏡電子能量分析器 ) Sample X-ray or e-beam radiation a R1 R2 Signal E = [Ke V/ ln(r 2 /R 1 ) ] E = K ev K is again the spectrometer constant. E-gun Deflected Electrons V Features of CMA: * high transmission * relatively low energy resolution * sensitive to sample position 15

16 dn/de At. Conc. Analysis Methods using AES Survey scan E-beam E-beam Depth profiling Ion beam E-beam Mapping E(eV) Depth (nm) 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 16

17 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. 17

18 Submicron defect analysis by Auger electron microscope Red: N, Green Al, Blue: Si A dot (0.25 mm)was found after the deposition of the blanket silicon oxynitride film and after the plasma etch of the film. The top of the dot off the patterned oxynitride feature is Al according to Auger analysis. Source : PHI 18

19 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. 電子束離子束能量分析器 (AES, ESCA) 原子濃度 B A 縱深 ( 濺蝕深度 ) 19

20 AES depth profiles for Ni(50 nm)/cr(50 nm) multilayer. Ni Cr (a) static sample, (b) rotating sample. 20

21 AES depth profiles for the interface between TaSix and Poly-Si films. TaSi x Si? 21

22 Thin gate oxidation with N 2 O Raw data SiO 2 Si SiOxN y Depth profiles 22

23 化學分析電子儀 ESCA (Electron Spectroscopy for Chemical Analysis) UPS 光電子 UV 光 K L M N XPS (X-ray Photoelectron Spectroscopy) X 光光電子儀 XPS 光電子 X 光 UPS (Ultra-violet photoelectron spectroscopy) UV 光光電子儀 E k = hn - E B E B = hn - E k where h: Planck constant, n: the photon frequency, and E B : the binding energy of the photoelectron. For a solid sample, E B = hν - KE - φ; φ: 試品功函數 (Work function) φ 23

24 Ultra-high Vacuum 球扇形能量分析器 X 光光源 X- 光檢測器 ~5 nm 光電子表面數具擷取系統 24

25 X-ray Intensity Light source for Photoelectron spectroscopy X 光 Al 窗 Twin-Anode X-ray Source 電子束燈絲陽極 Ka Energy HV Flux distribution of a typical x-ray source Filter Cutoff 冷卻水 1. Core Level Excitation 2. Deacceleration of Electrons (Bremsstrahlung) X-ray photoelectron excitation source Radiation Energy (ev) FWHM (ev) Y Mz Zr Mz Na Ka Mg Ka Al Ka Si Ka Ti Ka Cr Ka Cu Ka

26 Chemical Structure Study by ESCA F adsorbs on Si surface Ethyl trifluoroacetate BE(i) ~ E i + qk i Ei : 元素 (q=0) 電子 i 之束縛能 k: 常數, q: 原子上的電荷 26

27 Oxidation of the Si(100) surface studied by XPS with synchrotron radition (120 ev) 27

28 ESCA 能譜上的各種訊號峰 Silicon Auger C(KLL) O(KLL) X-ray satellite plasmon 28

29 ENERGY Doublet peaks Spin - Orbital angular momentum coupling induced energy splitting 13.2 ev Atomic energy level diagram ORBITALS N Shell M Shell 4f 4d 4p 4s 3d 3p 3s j STATES 7/2 5/2 3/2 5/2 1/2 3/2 1/2 3/2 5/2 1/2 3/2 1/2 L Shell 2p 2s 1/2 3/2 1/2 K Shell 1s 1/2 29

30 Scanning Auger Nanoprobe (AES) 工程六館材料系 Room FE215 30

31 E-gun Ion gun SEM detector Manipulator Energy analyzer Sample carrousel 試片轉盤 Load -lock Sample Turbo pump Ion pump Rotary pump 31

32 目前每週二四全天及三五早上共六個時段開放為委託分析服務時段服務辦法每週一下午及每週四晚上為教育訓練時段, 訓練學生儀器原理及儀器操作能力其餘時段則為具 A 級與 B 級操作資格學生之自行操作時段教育訓練開放對象主要以校內外博士班學生考試通過後, 可取得 B 級自行操作資格待 B 級執照操作時段滿 30 小時後, 始可接受 A 級操作資格訓練及考試 32

33 E N D 33

(Electron Spectroscopy) 3-2

III AES...3...7...11...12...14 1....14 2....18 (Depth Profile)...21...25 (Electron Spectroscopy) 3-2 Pierre Auger 1922 1923 30 P. Auger X (Auger ) AES 1. (Auger Effect) ' E L2,3 K L 1 (EK E ) L1 X ( XPS