材料学中常用的分析方法 第八讲 - FIB聚焦离子束技术

1、北京科技大学材料科学学院 唐伟忠 Tel: 6233 2475 E-mail: 下载信箱： 密码：123456ocused ion beam Background 1Beneath the surface, more is concealed: Often, after you see microstructures on the surface, you have a desire to get into the buried underlying, otherwise you get little from the surface. But with SEM or TEM, you can

2、 see, and you cant touch. Background 2A 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 of a device, you can not be sure whether you can do it by mechanically polishing and et

3、ching to obtain a useful sample. Background 3A 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 mechanical and electrical machines. When this is happening, we need dedicated machine tools

4、.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 ColumnA SEM, but its e-gun is replaced by an ion gun, with 10nm ion beam spot size. Commonly used hairpin

5、 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 to the tip where ions are field evaporated and ionized by high voltages, forming a highly

6、 bright ion beam. Ion species available: Ga In Au Au/Ge Alloy Au/Si Alloy Au/Si/Be Alloy As/Pd/B Alloy As/Pd Alloy .（LMIS） FIB: Liquid metal ion sourceLMIS socket with filament (c) filament filled with AuGeSi alloyL. Bischoff / Ultramicroscopy 103 (2005) 5966 FIB: Liquid metal ion sourceGenerally, 5

7、kV30kV acceleration voltage is used Emission current as a function of voltageJEM-9310 FIB Why a Dual-Beam FIB?Main elements of a Dual-Beam FIBFIB, SEM, Gas Injection (for deposition and etching), detectors for electrons, ions and X-ray q Local flooding of reactive gases at the surface can either pro

8、vide selective etching or selective deposition.q A low energy electron flood gun can be used to provide charge neutralization, and thus highly insulating samples may be imaged and milled without charging. E.S. Sadki et al. / Physica C 426431 (2005) 15471551Ion beam induced or assisted depositionDepo

9、sition of metallic or insulating film is achieved from induced decomposition of a precursorPt 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. q W deposition is poss

10、ible from a W(CO)6 precursor.q 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 res

11、olutions as SEM SIM & SIMS (scanning ion microscope & secondary ion mass spectroscopy) CCM (channeling contrast imaging, “grain contrast”)a tool for materials characterization with 3-10 nm resolutionFIB capabilities (machining): Sample processing ability (nano-patterning and machining) Sputt

12、ering/ Reactive etching Ion induced Deposition Shallow ion implantation a tool for materials fabrication with 10 nm tolerance Dual-Beam FIB capabilities a microscope turned into a workbenchanalysismask repair nano-machiningq Deposition: direct ultrafine deposition of metal or insulator (metals: W, A

13、u, Fe; insulators: SiO2, C) device modification nano-fabricationq Materials characterization imaging, mapping in all sections and orientations Imaging and Mapping Analysis SE images of a Au grid imaged with Mn2+ beamIIE: Surface imaging with Mn2+ FIBIIE: Magnetic domain imaged with Ga+ FIBThe image

14、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 the surface. Secondary Electron Image Comparison Spatial resolution of IIE and SEM images Total positive and negative SIMS im

15、ages 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 MCP (micro-channel plate) obtained by using an Au+ primary ion beam. The channel diameter

16、 is 10mSIMS: Surface imaging with FIB the position of the line shows the position where a cross-sectioning will be made Voltage contrast revealing open via positions in a circuitCross-sectioning and AnalysisM .A . Meyer et al . / Microelectronic Engineering 64 (2002) 375382 Void development at the c

17、athode end of a line P.J. Heard et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 244 (2004) 6771P.J. Heard et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 244 (2004) 67713D Tomographical AnalysisSEM of tire debris produced by normal wearM. Milani et al. / Materials Characteriz

18、ation 284 52 (2004) 283288Crystallization study of VOHPO42OL. OMahony et al. / Journal of Catalysis 227 (2004) 270281FIB enables 3D-EBSD capabilityJ. Konrad et al. / Acta Materialia 54 (2006) 13691380A precipitateFIB enables 3D-EBSD capabilityJ. Konrad et al. / Acta Materialia 54 (2006) 13691380FIB

19、enables 3D-EBSD capabilityJ. Konrad et al. / Acta Materialia 54 (2006) 13691380Lift-outH-bar or TrenchTo Prepare an H-bar TEM Sample with FIB Step 1 - Obtain an Aperture Grid with a 1mm hole, cut away a portion of the grid. OR ORTo Prepare an H-bar TEM Sample with FIB Step 2 - Create a Specimen Slic

20、e 1mm x 2.5mm, with the feature of interest positioned roughly in the center, and thin the slice to 60 m or less. To Prepare an H-bar TEM Sample with FIB Step 3 - Grid and Slice Come Together by using a TEM suitable adhesive. To Prepare an H-bar TEM Sample with FIB Step 4 Ion milling the slice to el

21、ectron transparency 100nmStep 1 Locate the Area of Interest Cross-sectional TEM sample preparation Automatic “lift-out” methodAn area, indicated by the arrow, was marked by “X”s by FIB. Step 2 FIB-deposit a Protective Pt Layer Pt was coated on the surface to protect the area from ion damage.Cross-se

22、ctional TEM sample preparation Automatic “lift-out” methodStep 3 Mill two trenches from the both sides Cross-sectional TEM sample preparation Automatic “lift-out” methodStep 4 Thin the Central region to Electron TransparencyCross-sectional TEM sample preparation Automatic “lift-out” methodAn U-shape

23、d cut was made, then the sample is ready to be “lift out” by an electrostatic probe. Step 5 Perform Frame CutsCross-sectional TEM sample preparation Automatic “lift-out” methodStep 6 FIB-mill to Free MembraneCross-sectional TEM sample preparation Automatic “lift-out” methodSE images showing the in s

24、itu lift-out procedureR.M. Langford, C. Clinton / Micron 610 35 (2004) 607611 The FIB Plan-View Lift-Out TechniqueFIB SE image of grain boundary corrosion (black area is insulating). Site-specific TEM Specimen Preparation ofGrain Boundary Corrosion in Ni-Based AlloysFIB ion image of the region. Oxyg

25、en enhanced ionization yield of the region making it appear white Site-specific TEM Specimen Preparation ofGrain Boundary Corrosion in Ni-Based Alloys Site-specific TEM Specimen Preparation ofGrain Boundary Corrosion in Ni-Based AlloysFIB SI image after a thin protective layer of W is deposited. It

26、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 TEM Specimen Preparation ofGrain Boundary Corrosion in Ni-Based Alloys Site-specific TEM Speci

27、men Preparation ofGrain Boundary Corrosion in Ni-Based AlloysFIB SE image of the region glued down on the carrier, ready for thinning to electron transparency. Site-specific TEM Specimen Preparation ofGrain Boundary Corrosion in Ni-Based AlloysTEM image (1,500X) of the final specimen mounted on the

28、carrier. 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 deposited onto the indent to protect the upper surface during subsequent milling. After etching through the structure, the cross section can be

29、 viewed by tilting the specimen in FIB.The right image is a top view of the completed TEM foil which is electron transparent.Degradation of TiN coating under cyclic indentationJ.M. Cairney et al. / Acta Materialia 52 (2004) 32293237Degradation of TiN coating under cyclic indentationJ.M. Cairney et a

30、l. / Acta Materialia 52 (2004) 32293237(a) FIB deposition of Pt protective layer over the device (b) Removal of bulk material on both sides of device areaA.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 fo

31、r lifting outA.C.K. Chang et al. / Thin Solid Films 496 (2006) 306 310FIB induced damages in metallic TEM sampleJ. Yu et al. / Materials Letters 60 (2006) 206209FIB induced damages in metallic TEM sampleJ. Yu et al. / Materials Letters 60 (2006) 206209FIB induced damages in Si/Si pn junction specime

32、nZ. Wang et al. / Applied Surface Science 241 (2005) 82 8086FIB induced damages in Si device specimenZ. Wang et al. / Applied Surface Science 241 (2005) 82 8086FIB induced damages in Si device specimenZ. Wang et al. / Applied Surface Science 241 (2005) 82 8086Damage of crystalline Ge by FIB millingS

33、. Rubanov, P.R. Munroe / Micron 35 (2004) 549556TEMMicro-machiningFIB Micromachining Capabilities FIB deposition and milling can produce features 200nm or lessW deposition can produce “drill bits” and other complex structures which is then FIB machined to a final shape. FIB Micromachining Capabiliti

34、es An “AFM tip” with aspect ratio larger than 50:1, machined to a point with a radius of curvature less than 40 nm. FIB Micromachining Capabilities Micromachining a micromachineA Si accelerometer is produced by conventional etching, then an angled cut is made by FIB because conventional etching acts

35、 normally to the substrate and because the cut is very deep. Fabrication of organized arrays of quantum dotsSchematic of Ga+ ion beam etching into Si3N4 mask J. Gierak et al. / Microelectronic Engineering 7374 (2004) 610614GaN dotsFabrication of organized arrays of quantum dotsThen GaN dots were sel

36、ectively epitaxially grown on Si3N4 masked AlN/SiC by FIB. J. Gierak et al. / Microelectronic Engineering 7374 (2004) 610614 SiNxGaNSEM imageTEM imageFIB-fabricated SiNx/Au bimorph cantileverJ. Teng, P.D. Prewett / Sensors and Actuators A 123124 (2005) 6086135m wide, attached to a Pt nano heater (da

37、tabar=15 m). When heated, deflection will occur.Pt heatercantileverSub-micron intrinsic Josephson junctionCritical current of a dc SQUID will oscillate when weak magnetic field changesS.-J. Kim et al. / Physica C 412414 (2004) 14011405Scanning ion-beam microscopy of sub-micronm2) intrinsic Josephson

38、 junctionPhysica C 426431 (2005) 14791483Intrinsic Josephson junction was cut from a YBCO single crystal whisker, consisting of superconducting CuO2 layers and a block layer with THz oscillation frequencyS.-J. Kim et al. / Physica C 412414 (2004) 1401140567% more efficient fiber-waveguide optical co

39、upling lens could be made by FIBF. Schiappelli et al. / Microelectronic Engineering 7374 (2004) 397404Efficient fiber-to-waveguide coupling lensfiber-waveguide coupled optical signalsEfficient fiber-to-waveguide coupling lensSEM image of FIB milled microlens (a) on top of the fiber tip and (b) its d

40、etailed view F. Schiappelli et al. / Microelectronic Engineering 7374 (2004) 397404FIB machined probes for electric force microscopySketch of Pt modified AFM tip and FIB fabricated and a Pt coated electric conductive SPM tipC. Menozzi et al. / Ultramicroscopy 104 (2005) 220225Single-edge-notched ten

41、sion specimen for fracture toughness measurementX. Li et al. / Sensors and Actuators A 117 (2005) 143150Single-edge-notched tension specimen for fracture toughness measurementX. Li et al. / Sensors and Actuators A 117 (2005) 143150FIB could introduce tiny notch to samples in any orientationsLaser cu

42、tFIB cutMicrocircuit Modification成象加工制样沉积Using FIB, viewing, cross sectioning, cutting of connections, deposition of conducting wires are all possibleSchematic of Device ModificationA: FIB Cut to Metal 1 B: FIB Via to Metal 1 C: FIB Via to Metal 2 D: FIB Strap Joining Vias Device ModificationA 0.15m

43、 device, with one bond pad isolated from the surrounding circuitry pad cut cutTo test a correction before re-fabrication, metal wires can be exposed, cut, re-conected, and Si02 insulated, over distances from m to mm. Thus an IC can be prototyped in hours.Device ModificationDevice ModificationA devic

44、e modified by connecting Metal 3 to Metal 1 through a 0.8 m wide hole filled with W. Metal 3 Metal 1 WMicrocircuit design errorsAn error in circuit design have serious effects. Correcting faults can take weeks.FIB offer an alternative in repairing chips in hours.Then, FIB and a suitable gas is direc

45、ted onto the fault, and W, Pt or SiO2 may be deposited. Also cuts may be made into the samples. Modifications made to a microchip. As+ implantation and A.J. De Marco, J. Melngailis / Solid-State Electronics 48 (2004) 18331836SEM imageSEM of structure with W electrodes connected by Al pads but separated by SiOx layerM. Prestigiacomo et