1Some FIB AppsIan R. HarveyMicroSystems Design and CharacterizationDb-FIB System ConfigurationSFEG ElectronColumnIon Column VacuumChamberChamber depicted here is an 8” dualbeamMicroSystems Design and CharacterizationCoincident PointIon BeamElectron BeamTilt axisMicroSystems Design and CharacterizationRow Bar Cross sectioningWhat is a cross section?• FIB removes small amount of material leaving a perpendicular wallfor imaging• SEM takes an image from an angle to measure the previously buriedfeatureSEM:ImagingFIB: CuttingMicroSystems Design and CharacterizationSome thoughts on FIB: Materials characterization Channeling contrast (microstructure / texture) Surface sensitive / multiple contrast mechanisms Coupled with mass-spec ==> SIMS Coupled with SEM/EDX ==> Amazing! Process characterization In-situ precision cross-section / staining TEM sample preparation (precision sites) Prototype development Mod: Selective dep and etch of metals/dielectrics Custom micromachining using CAD fileSEM/FIB are Foundational tools of Microsystems!!MicroSystems Design and Characterization“Differential Discharge” sites…MicroSystems Design and CharacterizationDevice Passivation Damage…MicroSystems Design and CharacterizationDual-Beam FIB characterization:SEM-mode replication…MicroSystems Design and CharacterizationFollowed by FIB coarse section……and SEM inspectionMicroSystems Design and CharacterizationFinal polish with a fine ion beam……and in-situ SEM inspectionMicroSystems Design and CharacterizationOptical(plan view)Decap / peek…SEM(secondary e signal)MicroSystems Design and CharacterizationWhich layer is weak?MicroSystems Design and CharacterizationWhich layer is weak?MicroSystems Design and CharacterizationSome Imaging Tools SE: Microchannel Plate BSE: (fromMicroSystems Design and CharacterizationFIB Channeling ContrastMicroSystems Design and CharacterizationFIB Channeling Contrast Al / 2% Cu 70µm FOV Note Cu ppts Uniform dist’n Pinned grainsMicroSystems Design and CharacterizationFIB Channeling Contrast Al / 0.5% Cu Sputt 200°C Annealed 450°C 20µm FOVMicroSystems Design and CharacterizationFIB Channeling Contrast Al / 0.5% Cu Sputt 300°C Annealed 450°C 20µm FOVMicroSystems Design and CharacterizationFIB Channeling Contrast Al / 0.5% Cu Sputt 400°C Annealed 450°C 20µm FOV20MicroSystems Design and CharacterizationPassive Voltage Contrast (SEM)http://www.acceleratedanalysis.com/hepvc.htmlAs a rule of thumb, the primary beam of a SEM penetrates IC materials about 1000!Å per1000 eV of beam energy.! A 10 keV beam will penetrate about 1 micron.! An isolatedconductor covered with one micron of passivation will become negatively charged due tothe build up of electrons trapped from the beam.! Grounded conductors remain neutral aselectrons flow away.MicroSystems Design and CharacterizationElectromigration <== e- “wind” From V. Chowdhury& D. Pramanik VLSI Metallization& interconnectsconference Al 1% Cu 2mA/cm2 200°C Look for 30%change in resistance Or else…Some via chain structures arehave a bit more obvious defects!MicroSystems Design and CharacterizationElectromigrationMetal pile-up due to cumulative momentum Xfer <== e- “wind”MicroSystems Design and CharacterizationUse of FIB to verify change incircuit…MicroSystems Design and CharacterizationMark area of interest & examineMicroSystems Design and CharacterizationTrace routing metal…MicroSystems Design and CharacterizationCharacterization of Scribeline Generated Defects on a 0.8um CMOS processH. Sur and A. BarmanVLSI Technology, Inc. San Jose CAISTFA ‘93 Los AngelesMicroSystems Design and CharacterizationMicroSystems Design and CharacterizationIR + Si ==>window thru backsideMicroSystems Design and Characterization…backside EmMiMicroSystems Design and CharacterizationBackside probing for verification…MicroSystems Design and CharacterizationBackside probing for verification…MicroSystems Design and CharacterizationBackside Si-removal by LCE:Laser Chemical Etch Ar or doubled YAG + Cl2MicroSystems Design and CharacterizationFIB