FEI 430 Nova NanoSEM - Engineering Research

FEI 430 Nova NanoSEMIntroductionThe FEI 430 NanoSEM is a field emission scanning electron microscope with high resolutionimaging down to several nm features using its range of backscatter and through-lens detectors.This microscope can image samples ranging from small pieces to 4-inch wafers. It is alsoequipped with a platinum deposition tool and a NPGS electron beam lithography system.Characteristic Light MicroscopePrinciple ofDetectionLight passingthrough glasslensesScanning ElectronMicroscopeScattered Electrons fromfield emission source usingelectromagnetic principles.DataGathered-Sample surface-Large area-2-D images aboutthe morphology ofany large structure-Sample surface-Less than 1 mm area-Topography and chemicalcontrast of powders, IC chips,etched microstructuresSample PrepNoneExpectedResolutionMicronsMount to sample stub.Insulating, biological, andpowder samples requireextra sample preparation.Several nanometersTransmission ElectronMicroscopeTransmitted electrons throughthin sample from field emissionsource using electromagneticprinciples.-Internal composition and atomicarrangement-Approx. 1 micron x 1 micron-Internal structure of dislocations,tiny precipitates, grain boundariesand other defect structuresMust be electron transparent(50-100nm thin)Sample viewing area limited byquality of sample prepSeveral Angstroms

Tool Capabilities Up to 5nm of ResolutionBackscatter and Secondary Electron imaging with Immersion Lens ModeWorking Distance: 5mm, Max HV: 30KeV with up to 5KeV stage biasPlatinum DepositionElectron Beam Lithography see: NPGS Electron Beam Lithography ManualFor EDS, EBSD, or FIB capabilities see: Oxford EDS, Oxford EBSD, or Scios FIB manualSuggested Documentation“A Guide to Scanning Microscope Observation” JEOL USA Electron optics documentsFEI System Operation Manualwww.fei.com/resourcesTool qualification policyThis document is intended to supplement but does not replace formal training andqualification by staff. In order to gain unsupervised access, the user must attend a 2-hourdemonstration and then pass a qualification test. The lab member must demonstrate safe andknowledgeable operation of the microscope without any interference from the instructor.Please contact Rijuta Ravichandran (rravicha@ucdavis.edu) to set up a demonstration, practice,or potential imaging service work.Precautions and safetyPlease take into consideration the following when working around the microscope:ALWAYSWear gloves when touching anything thatgoes into the chamber:-Samples-Sample holders or mounts-Any part of the stageExercise care when working around thestage, it is fragileWatch the CCD camera to ensure thesamples and the stage is clear from theother microscope parts (i.e. pole piece)NEVERTouch items that make contact with thechamber with your bare hands orcontaminated gloves:-Do not touch face or clothes-Do not touch computer-Do not touch dusty surfacesOpen or close the door too quicklyMake large stage movements, or tilt stagewithout watching the CCD camera in quadscreen viewing mode

Sample ConsiderationsThe following chart describes materials that are permissible within the microscope:ALLOWED-IC chips and MEMS devices-Cured photoresist, PDMS, or other polymers-Ceramics, glass, or insulating materials-4-inch wafers to pieces-Side and tilted viewsNOT ALLOWED-Magnetic materials-Biological Samples (without prep)-Outgassing materials:-Uncured photoresist-Oils, solvents, or any liquids-Loose powdersSample preparationA set of sample preparation mounts, conductive tape, and tweezers are available for communaluse in the SEM room. All of these materials must be placed inside the clear boxes to avoid dust andcontamination. ONLY use vacuum compatible tapes provided by CNM2. Samples should be thoroughlydegreased and dried to eliminate outgassing from organic contamination and water. Samples can becleaned with solvents such as isopropanol and then dried using compressed nitrogen. Loose surfaceparticles from cleaving wafers can also be removed by blowing the surface with nitrogen.Most samples should be mechanically clamped using the copper pin-clip sample holder (Fig. 1).If the sample is too large or too small for the pin-clip holder, then these samples can be mounted usingadhesives (Fig.2). Large pieces and crushed pellet samples may be mounted onto a stub with adhesivesor paste. Please contact staff for direction on mounting powders or imaging biological samples. Silverpaste must be left to cure overnight or for one hour with the use of a sample heater. For good measure,there is pressurized nitrogen available to remove any dust or loose debris from the sample’s surface.45/90-degree angle sample mounts are available for side and tilted sample views.Samples that have insulating properties will create charging effects that will cause imagedistortion or drift. These effects are caused by electrons building on the sample’s surface. Therefore, it isnecessary to create a conductive path for these electrons to prevent them from accumulating on thesample’s surface. This is done by using conductive holders, adhesives, and in addition sputter coating athin layer of conductive material on the surface.It is highly recommended to sputter coat insulating samples (oxides, cured polymers, etc) with athin layer of conductive material. First mount the sample either with a pin-clip holder or on top of stubwith conductive adhesives (Fig. 1,3). Then use the QuorumTech150 to coat a thin layer (1-10nm) ofcarbon or gold. After the sample has been coated it can go directly into the SEM for imaging.See: QuorumTech150 manual for more information on its operationFig 1. (Left) Sample mounted using pin-clip holder. Most samples can be mounted this way.Fig 2. (Right) If samples are oddly shaped, too small, or too big for the pin-clip holder, then usingadhesives is acceptable for these cases.

System OverviewHardwareMicroscope SystemControlsNPGS EBL SystemControlsSEM: Nova NanoSEM 430Note: Do not leave items/leanon area around chamber doorSwitch box: to flipbetween Supportand Control PCImaging andAlignment knobsESC: ABORT ACTIONMouse and Keyboard formicroscope controlsSupport PC: NoMicroscope Control.Internet access andUSBs OKControl PC: NO USBs,Microscope Controlsonly

ElectronColumnChamberChamber door handleStage control knobsOperating light:Green-OKYellow or black-SeeEverhart ThornlyDetectorCCD camera located onback of chamber wallPole PieceCoarse Lens Align (X)Coarse Lens Align (Y)Aperture selectionStage/Sample holder,can hold up to 7 samplesBeam blanker for EBL:DO NOT TOUCH

SoftwareSoftware Controlpages (see listbelow)Imaging is pausedMicroscopemode: HighVacuumSelected imagingwindow. Shown: ETDPole PieceBlue bar: Active windowScreen not pausedMicroscopeimaging: ETD,TLD, CCD viewsCCD window showsinside of chamberPage ListBeam ControlMicroscopestatusStage loweredMain FeaturesDetectorsPump/Vent chamber, Beam On/Off, Column: Spot Size and HighVoltage, Alignments, Microscope StatusDetector Settings: Detector type and mode, Grid VoltageBeam Deceleration ControlApply beam deceleration voltage or stage biasNavigationMove stage position, apply tilt, and tracking Z-heightPatterning: PlatinumDepositionProcessing/MeasurementPlatinum patterning: heater, patterning progress and controlsAlignmentsMeasurement tools, post processing: Digital brightness, contrast,and gammaStigmator centering alignment

OperationSystem pre-checkMake sure you have logged into Badger and have checked the logbook and Badger for any issues withthe tools. Then Enable the tool on Badger.Make sure the green light on the front of the machine ison. If it is yellow or turned off then do not use themachine and report the problem to staff.

If the Microscope XT program is not open already, find the XT server icon and double click to startthe program.XT Microscope ServerAs soon as the program is open, the log-on window will pop-up.After you have logged into the program, theapplication status window may pop-up. If itdoes, then alert staff with any issues that isdisplayed (I.e. Cooling water interlock failure)

If there are no issues, then check the status window in the bottom right of the screen.Chamber pressure: 1x10 -6-1x10 -5Gun pressure: 1x10 -10 to 1x10 -7Emission current: 100uA, or check previous log book entry ( /- 10% of thisvalue)The bright green symbols forboth electron gun and chamberindicate that the microscope isat high vacuum.Check for the bright green bar toindicate that the electron emissionsource is ready. If this bar is whitethen contact staffStart-up and Loading SamplesIf all steps from the pre-check list are completed without concern, it is OK to continue. Press “Vent” in the top right corner of the screen, amessage will pop-up for the user to proceed withventing the chamber.MAKE SURE THE SYSTEM IS ON “HIGH VACUUM MODE”The bright green section of the chamber icon will turn orange toindicate that the system is no longer in high vacuum. Once youhear the hissing sound from the chamber, it is ok to open thedoor and load in the samples. MAKE SURE CCD CAMERA ISUNPAUSED BEFORE PROCEEDING. (Short key: F6)Always watch the CCD camera when opening and closingthe chamber door!!Please consult with staff before attempting to image crosssections or tilted samples. These samples require specific precautions as tall samples may crash into thepole-piece within the microscope chamber.

Press “Pump” to bring the chamber back under high-vacuum. Place one finger on the door untilthe door seals and the roughing pump initiates.While the chamber is pumping down, raise the stage such that the surface of the sample is inline with the 5mm marker. To do so, press down on the center wheel and drag the arrowupwards.After the sample has been raised, click on the imaging window and continue to set up the imagingparameters. Select the appropriate spot size and accelerating voltage for your sample Go to the detectors menu, make sure the system is using the ETDdetector in secondary or backscatter electron mode and that thegrid voltage is set to 250V.Once the chamber is under high-vacuum (check microscope status icon),you will be able to turn on the beam and begin imaging. ImagingTurn on the Beam by pressing the “HV button” —you will start infield free modeAdjust the dwell time, resolution, and filter mode (number of frames)Dwell Time (tdwell): The time the beam spends on a singlepixel per pass. Changing this influences the Total Depth andTotal time, assuming a constant Number of passes.Resolution: no. of points or pixels, Width x Height (image resolution)

Clicking on the down-arrow next to the icon (filtermode) displays menu items Live / Average /Integrate, Number of Frames enabling to selectnumber of averaged or integrated images Lowest magnificationMove to the location of the sample and find area with high contrast or to the corner of sampleFull screen (Shortkey : F5)Adjust brightness/contrast using the videoscope (Short key: F3) and/or using the histogramunder the processing menu. Watch out for bright and dark peaks.