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1、材料学中常用的分析方法 Instrumental Analysis in Materials Science,北京科技大学材料科学学院 唐伟忠 Tel: 6233 2475 E-mail: 下载信箱：wztang_ 密码：123456,第八讲,FIB（Focused ion beam） （聚焦离子束技术）,Background 1,Beneath the surface, more is concealed: Often, after you see microstructures on the surface, you have a desire to get into the burie
2、d underlying, otherwise you get little from the surface. But with SEM or TEM, you can see, and you cant touch.,Background 2,A dedicated world to be explored in every detail: Microelectronic components are getting smaller and smaller. And if you would like to see inside the complicated 3D structure o
3、f a device, you can not be sure whether you can do it by mechanically polishing and etching to obtain a useful sample.,Background 3,A micro- and nanometer scaled world to create: Rapidly, we are moving towards a micro- and nanometer world: micro- and nano-sensors, actuators and various kinds of mech
4、anical and electrical machines. When this is happening, we need dedicated machine tools.,What is an FIB? FIB is just like a normal SEM, but its e-gun is replaced by an ion gun. The advantage of FIB lies in ions mass, orders of magnitude heavier than that of electrons.,A Ga+ ion beam Column,A SEM, bu
5、t its e-gun is replaced by an ion gun, with 10nm ion beam spot size.,Commonly used hairpin source: a W filament and a coil are attached to a ceramic base and coated with liquid metal in a high vacuum. During operation, the metal is melted by resistive heating, allowing capillary flow of liquid metal
6、 to the tip where ions are field evaporated and ionized by high voltages, forming a highly bright ion beam.,液态金属离子源（LMIS）,常用的液态金属离子源（LMIS）,LMIS socket with filament (c) filament filled with AuGeSi alloy,L. Bischoff / Ultramicroscopy 103 (2005) 5966,Generally, 5kV30kV acceleration voltage is used,Emi
7、ssion current as a function of voltage,真空中，液体离子源的金属原子被场蒸发和场离化，加速、聚焦后形成聚焦的离子束。 直径10nm的聚焦离子束扫描于样品表面，激发出二次电子、二次离子等，提供高分辨率的图象；同时，离子束引发物质的溅射效应。,Dual column FIB,Jeol Fabrika: Jeol 6500F SEM with Orsay Physics Ion Column,Why a Dual-Beam FIB? Dual-Beam FIB is a combination of SEM with a FIB,Main elements of
8、 a Dual-Beam FIB,FIB, SEM, Gas Injection (for deposition and etching), detectors for electrons, ions and X-ray ,Local “flooding“ of reactive gases at the surface can either provide selective etching or selective deposition. A low energy electron flood gun can be used to provide charge neutralization
9、, and thus highly insulating samples may be imaged and milled without charging.,E.S. Sadki et al. / Physica C 426431 (2005) 15471551,Ion beam induced or assisted deposition,Deposition of metallic or insulating film is achieved from induced decomposition of a precursor,Ion beam assisted deposition &
10、etching in FIB,Pt film could be deposited on sample surface by directing an organometallic compound precursor, (CH3)3CH3C5H5Pt, dimethyl-methyl-cyclopentadienyl-Pt, with Ga+ ion beam scanning the area. 1m thick layer could be deposited in 3-10 min. W deposition is possible from a W(CO)6 precursor. E
11、tching is also possible in I2 atmosphere.,Dual-Beam FIB capabilities “a microscope turned into a workbench”,Dual-beam FIB capabilities: SEM capabilities: SE and BE imaging EDX, AES EBSD FIB capabilities (analysis): IIE (ion induced electron microscopy) imaging with similar resolutions as SEM SIM & S
12、IMS (scanning ion microscope & secondary ion mass spectroscopy) CCM (channeling contrast imaging, “grain contrast”),a tool for materials characterization with 3-10 nm resolution,FIB capabilities (machining): Sample processing ability (nano-patterning and machining) Sputtering/ Milling Reactive etchi
13、ng Ion induced Deposition Shallow ion implantation,a tool for materials fabrication with 10 nm tolerance,Dual-Beam FIB capabilities a microscope turned into a workbench,FIB applications:,Removal of materials: sectioning and slicing for further analysis TEM specimen preparation in hours of time devic
14、e modification and mask repair nano-machining with high degree of site specific precision Deposition: direct ultrafine deposition of metal or insulator (metals: W, Au, Fe; insulators: SiO2, C) device modification nano-fabrication Materials characterization imaging, mapping in all sections and orient
15、ations,Imaging and Mapping Analysis,FIB象衬度的形成机制 接收FIB感生的电子、离子，可形成如下的衬度： * 拓扑衬度 当离子束入射到不规则的样品表面时，二次离子、电子的产额依赖于不同部位处离子束的入射角。不同部位处入射角不同，二次电子、离子的产额也不同。低能的二次电子的逃逸距离1-50nm，而二次离子的逃逸距离1nm。因此，二次离子只携带样品浅层表面的信息。这时, 二次电子、离子形成的衬度是拓扑衬度 * 成分衬度 与SIMS时相似，二次离子的产额取决于表面成分和表面污染层的情况。表面氧化物层的存在，基体成分的相互影响效应，离子束引发的表面化学变化等因素均
16、影响二次离子的产额。这使得二次离子象产生独特的成分衬度。,FIB象衬度的形成与分类 * 通道效应衬度 二次电子、离子的产额还依赖于晶体相对于入射束的取向。当入射束方向与低指数方向重合，离子束进入晶体内很长距离才会停下来，即入射离子产生了通道效应。这导致离子与样品表面原子作用几率和表层二次电子产额显著降低，因而显示出通道效应衬度(晶粒衬度)。 * 电位衬度 二次电子、离子的能量较低，导致其逃离样品表面的能力取决于表面的电位。离子的速度小，其逃逸能力更小，因而绝缘样品的表面易于形成正电荷积累。绝缘体的不同部位（不同导电率）处积累不同的电位，则二次电子发射几率产生变化，形成电位衬度。,SE imag
17、es of a Au grid imaged with Mn2+ beam,IIE: Surface imaging with Mn2+ FIB,IIE: Magnetic domain imaged with Ga+ FIB,The image shows magnetic domain pattern in a magnetic film. The image was taken by FIB SE imaging. The contrast is a consequence of deflection of electrons by local magnetic field near t
18、he surface.,Spatial resolution of IIE and SEM images,Total positive and negative SIMS images of an Al mesh. The negative ion image is much clearer than the positive one, because it contains not only secondary ions, but also secondary electrons.,SIMS: Surface imaging with FIB,SIMS image of a cracked
19、MCP (micro-channel plate) obtained by using an Au+ primary ion beam. The channel diameter is 10m,SIMS: Surface imaging with FIB,Voltage contrast revealing open via positions in a circuit,As ions are heavier than electrons, they could sputter materials, in addition to excite secondary electrons and i
20、ons from the samples.,Cross-sectioning and Analysis,FIM 样品断面分析的步骤,Advantages: precisely cut at the right location free of artifacts introduced during dicing, grinding, polishing, etc（?!）,证明了缺陷与基底材料的形貌密切相关，而薄膜的厚度则是均匀的,薄膜的表面缺陷及断面FIB象,显示：不同厚度的薄膜中，不仅有柱状晶、织构，且存在晶粒的异常长大,Micrographs and schematics of Ag fi
21、lm microstructures (with different thickness),After cutting the film with FIB, the buckle geometry and the discontinuity revealing film stress relaxation.,Image of a telephone cord buckle on a DLC film,A: Pt保护层, 其下面为厚度10微米的表面腐蚀层,腐蚀后的1018 C钢的 FIB 断面象,涂层磨损区断面的 FIB 观察,磨损前、后断面的IIE通道衬度象显示,柱状晶上部被磨损作用力所扭曲（
22、图象上部是沉积的Pt层）,A failure feature within conductive lines: void formation,集成电路中元素的电迁移,M .A . Meyer et al . / Microelectronic Engineering 64 (2002) 375382,The time difference between the imaging is 2 hours. Void formation results in a failure.,Void development at the cathode end of a line,FIB section of
23、 ink penetration into clay coated paper,P.J. Heard et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 244 (2004) 6771,(a) Low and (b) high magnification SEM of FIB-prepared ink printed paper. Clay has been used to coat the paper.,FIB section of ink penetration into clay coated paper,P.J. He
24、ard et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 244 (2004) 6771,(a) Low and (b) high magnification SEM: significant ink penetration into the coating is visible, leading to waste of ink,3D Tomographical Analysis,（a）选择区域，沉积Pt 溅射保护层，切割 （b）倾斜进行断面观察 （c）重复a, b过程 （d）使用计算机将2D图象组合为3D图象,3D-FIB
25、观察过程的示意图,Parallel 2D FIB cross-sections indicate pile-up of material (arrow).,Fracture damage under the scratch grooves in Al2O3,为使相邻晶粒显示通道衬度，在两个角度上进行了衬度观察,FeAl材料中各晶粒的3D-形貌的重组象,先倾斜80度做截面切割，然后转回30度，收集截面A的成分分布象。重复如上的过程，逐次获得B, C截面的成分图,3m，涂敷有0.15m-SiO2的TiO2颗粒的成分分布,By ion beam image of tire debris, inter
26、nal microstructure was observed, without any preparation,SEM of tire debris produced by normal wear,M. Milani et al. / Materials Characterization 284 52 (2004) 283288,Rosette crystal (a) may be cut by FIB (b) and analyzed,Crystallization study of VOHPO40.5H2O,L. OMahony et al. / Journal of Catalysis
27、 227 (2004) 270281,With FIB, successive slices of material (minimum thickness 50nm) can be removed. EBSD and EDX analysis can construct 3D image of the original microstructure,FIB enables 3D-EBSD capability,J. Konrad et al. / Acta Materialia 54 (2006) 13691380,A precipitate,Maps of average misorient
28、ation at two nearby sections,FIB enables 3D-EBSD capability,J. Konrad et al. / Acta Materialia 54 (2006) 13691380,3D view in vicinity of a Laves-phase particle. The Laves phase is colored blue. The warm-rolled Fe3Al phase with small misorientation of less than 2.5 are colored gold,FIB enables 3D-EBS
29、D capability,J. Konrad et al. / Acta Materialia 54 (2006) 13691380,TEM Specimen Preparation,TEM specimen preparation In most cases a particular region is important to TEM investigation. Using the FIB it is possible to locate the feature from the top surface of the specimen and cut the structure so a
30、s to leave a thin foil remaining. The pictures below show a typical fabrication sequence.,FIB制备TEM 样品的两种方法,Lift-out,H-bar or Trench,OR,OR,To Prepare an “H-bar“ TEM Sample with FIB Step 4 Ion milling the slice to electron transparency 100nm,Cross-sectional TEM sample preparation Automatic “lift-out”
31、method,An area, indicated by the arrow, was marked by “X”s by FIB.,Pt was coated on the surface to protect the area from ion damage.,Cross-sectional TEM sample preparation Automatic “lift-out” method,Cross-sectional TEM sample preparation Automatic “lift-out” method,Trenches are milled until electro
32、n transparent (less than 100nm).,Cross-sectional TEM sample preparation Automatic “lift-out” method,An U-shaped cut was made, then the sample is ready to be “lift out” by an electrostatic probe.,Step 5 Perform “Frame Cuts“,Cross-sectional TEM sample preparation Automatic “lift-out” method,Cross-sect
33、ional TEM sample preparation Automatic “lift-out” method,SE images showing the in situ lift-out procedure,R.M. Langford, C. Clinton / Micron 610 35 (2004) 607611,The FIB “Plan-View Lift-Out“ Technique FIB SE image of grain boundary corrosion (black area is insulating).,Site-specific TEM Specimen Pre
34、paration of Grain Boundary Corrosion in Ni-Based Alloys,FIB ion image of the region. Oxygen enhanced ionization yield of the region making it appear white,Site-specific TEM Specimen Preparation of Grain Boundary Corrosion in Ni-Based Alloys,Site-specific TEM Specimen Preparation of Grain Boundary Co
35、rrosion in Ni-Based Alloys,FIB SI image after a thin protective layer of W is deposited. It serves also as a marker of the original surface.,Top and off-axis FIB SE views of the region milled free of the surrounding material. A small support holds the region in place until lift-out.,Site-specific TE
36、M Specimen Preparation of Grain Boundary Corrosion in Ni-Based Alloys,Site-specific TEM Specimen Preparation of Grain Boundary Corrosion in Ni-Based Alloys,FIB SE image of the region glued down on the carrier, ready for thinning to electron transparency.,Site-specific TEM Specimen Preparation of Gra
37、in Boundary Corrosion in Ni-Based Alloys,TEM image (1,500X) of the final specimen mounted on the carrier.,TEM imaging of a nano-indented multilayer Usually a particular region is important, and specimen must be cut so that a thin (1um) section contains the region of interest.,A Pt film is first depo
38、sited by FIB onto the indent to protect the upper surface during subsequent milling.,By etching around the interesting site, thin foils are available to TEM observation.,TEM imaging of a nano-indented multilayer,H-bar,After etching through the structure, the cross section can be viewed by tilting th
39、e specimen in FIB. The right image is a top view of the completed TEM foil which is electron transparent.,TEM imaging of a nano-indented multilayer,TEM image of the multilayer. The distortion of the surface layer is obvious.,TEM imaging of a nano-indented multilayer,No plastic deformation occurs wit
40、hin the grains. Intergranular cracks appear, C.,Degradation of TiN coating under cyclic indentation,J.M. Cairney et al. / Acta Materialia 52 (2004) 32293237,FIB SE shows cracks between columnar grains, X and few transgranular cracks, Y. Steps S appear at the base of the coating due to shearing of co
41、lumnar grains. Channelling contrast appears between different heavily deformed grains in the steel substrate, Z.,Degradation of TiN coating under cyclic indentation,J.M. Cairney et al. / Acta Materialia 52 (2004) 32293237,(a) FIB deposition of Pt protective layer over the device (b) Removal of bulk
42、material on both sides of device area,TEM sample preparation: a MOSFET device,A.C.K. Chang et al. / Thin Solid Films 496 (2006) 306 310,(c) Finely thinned and polished TEM lamella (d) TEM lamella cut free from wafer, ready for lifting out,TEM sample preparation: a MOSFET device,A.C.K. Chang et al. /
43、 Thin Solid Films 496 (2006) 306 310,TEM of IF steel sample near FIB fabricated portion with EDX analysis: Ga incorporation,FIB induced damages in metallic TEM sample,J. Yu et al. / Materials Letters 60 (2006) 206209,high magnification TEM near FIB irradiated area,FIB induced damages in metallic TEM
44、 sample,J. Yu et al. / Materials Letters 60 (2006) 206209,New phase formation,FIB prepared specimen for observing sidewall-damaged layer,FIB induced damages in Si/Si pn junction specimen,Z. Wang et al. / Applied Surface Science 241 (2005) 82 8086,Low and high magnification view of damaged a-Si layer
45、s,FIB induced damages in Si device specimen,Z. Wang et al. / Applied Surface Science 241 (2005) 82 8086,Thickness of a-Si layers induced by 10 and 20keV Ga+ FIB,FIB induced damages in Si device specimen,Z. Wang et al. / Applied Surface Science 241 (2005) 82 8086,Ion beam induced cellular relief on G
46、e and its TEM,Damage of crystalline Ge by FIB milling,S. Rubanov, P.R. Munroe / Micron 35 (2004) 549556,cellular relief,TEM,Micro-machining,FIB deposition and milling can produce features 200nm or less,By scanning the ion beam to stimulate chemical reactions, a metal or insulating line can be easily
47、 drawn.,Schematic illustration of FIB-CVD growth,Si上FIB加工获得的显微场发射电极,FIB can achieve spot sizes of less than 50 nm. By comparison, laser repair reaches its limit at 2 m and optical lithography at 0.18 m .,FIB 在不同高分子材料上获得的加工图形,Not only metallic materials, but also polymers can be micromachined.,Microm
48、achining a micromachine,A Si accelerometer is produced by conventional etching, then an angled cut is made by FIB because conventional etching acts normally to the substrate and because the cut is very deep.,Fabrication of organized arrays of quantum dots,Schematic of Ga+ ion beam etching into Si3N4 mask,J. Gierak et al. / Microelectronic Engineering 7374 (2004) 610614,GaN dots,Fabrication of organized arrays of quantum dots,Then GaN dots were selectively epitaxially grown on Si3N4 masked AlN/SiC by FIB.,J. Gierak et al. / Microelectronic Enginee