Tescan Vega 3 Sem Instructions For Use Manual Download Page 20 | Manualshive

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Vacuum Modes

20

VEGA 3 SEM

Configuration of the apertures in the electron column

high and medium vacuum mode

low vacuum mode

5.1

High Vacuum Mode

In high vacuum mode, it is possible to investigate both conductive and non-conductive
samples; however non-conductive samples require previous metal coating (Cr, Au, Au-Pd,
Pt). All displaying modes are available.

5.2

Medium Vacuum Mode

In the medium vacuum mode - up to 150 Pa, it is possible to examine samples using all the
displaying modes, because the differential pumping aperture is located in the upper
position.

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Summary of Contents for Vega 3 Sem

Page 1: ...Scanning Electron Microscope Instructions For Use ...

Page 2: ... express written authority Offenders are liable for damages All rights reserved We have checked the contents of this manual for agreement with the hardware and software described Since deviations cannot be precluded entirely we cannot guarantee full agreement 2011 TESCAN a s Brno Czech Republic ...

Page 3: ...Chamber and Sample Stage 18 5 Vacuum Modes 19 5 1 High Vacuum Mode 20 5 2 Medium Vacuum Mode 20 5 3 Low Vacuum Mode 21 6 Detectors 22 6 1 SE Detector 22 6 2 LVSTD Detector 22 6 3 BSE Detector 23 6 4 CL detector 24 6 4 1 Exchange of CL for BSE lightguide 24 6 5 Other Detectors 25 7 Control Elements 26 7 1 Keyboard 26 7 2 Mouse 26 7 3 Trackball 27 7 4 Control Panel 27 8 Getting Started 28 8 1 Starti...

Page 4: ...fter a Filament Exchange 42 9 4 Mechanical Gun Centering 44 9 5 Aperture Exchange 44 9 5 1 Exchange of the Aperture Holder 45 9 5 2 Insertion of the Low Vacuum Aperture Holder 45 9 6 Cleaning the Column 46 9 6 1 Types of Contamination or Impurities 46 9 6 2 Cleaning the Column Parts 47 9 6 3 The Frequency of Cleaning 49 9 7 Specimen Holders 49 ...

Page 5: ...are for microscope control using a Windows platform Fully automated microscope set up Comprehensive software for image archiving processing evaluation and network operations comes as standard Minimal requirements on space power supply and environment Currently the VEGA 3 family includes several models of microscope fitted with various chambers according to the user s requirements for chamber size ...

Page 6: ... alloy blinds can cause an emission of dangerous ionizing radiation The microscope is provided with a number of automatic protections making unsuitable usage impossible e g it is not possible to switch on high voltage sources if the specimen chamber or electron gun space are open or are not evacuated to the working vacuum The deactivation of these protections can cause destruction of the machine a...

Page 7: ...oratory is ready technicians of the manufacturer or technicians of an approved company will carry out the installation connection to the mains and user training The customer is not allowed to connect the microscope to the mains or do any other manipulation except moving the microscope to the storage place The installation company will fill in the installation protocol The warranty period will star...

Page 8: ...lled the aperture angle The wider the cone the lower the depth of focus The beam intensity BI is the number of electrons passing through the probe in a defined time The image noise of the electron microscope depends on the number of electrons used for the information collected from each picture element It is necessary to use more time for image scanning at low beam intensity and vice versa It is e...

Page 9: ...etween the Wehnelt cylinder and the anode determinates the accelerating voltage of electrons and thus their energy The electron flow from the gun is specified with the emission current The emission current can be changed by applying negative potential between the Wehnelt cylinder and the cathode bias The whole gun system works as a virtual source of electrons with the following specifications the ...

Page 10: ... 50 µm The auxiliary lens IML is a magnetic lens used for the aperture change of the beam entering the lens OBJ or for displaying if the OBJ is off The change of the IML excitation causes the shifting of the electron beam across the optical axis and therefore it is necessary to compensate this shifting by means of the centering coils IML Centering The Stigmator is an electromagnetic octupole It is...

Page 11: ...hout IML lens The aperture is nearly optimal for lower BI values small spot size low beam current short working distances 4 5 mm and for the accelerating voltage 30 kV The pivot point of the scanning and the electric image shifts are close to the principal plane of the objective OBJ so that the curvature of the field distortion and field of view are as good as possible The centering of the objecti...

Page 12: ... auxiliary lens IML being switched on Characteristics good resolution increased depth of focus The aperture of the final beam is lower but the spot size is bigger in comparison with the RESOLUTION mode The beam in the probe stays unchanged This mode is used if it is necessary to have a greater depth of focus ...

Page 13: ...iddle beam and thus does not need to pass near the centre of the objective OBJ The position of the pivot point of scanning is optimized according to the field of view The centering coils IML center the supplemental intermediate lens IML to avoid image movement during focusing The DC component of the scanning coils is set up so that no image shift occurs if switched from the RESOLUTION mode to the ...

Page 14: ... minimized only available for post 2007 devices Highly excited objective multiplies the deflection of the beam The aperture of the beam is very small and the depth of focus is very high The IML Centering coil serves for minimizing the image shift when focusing The mode is used to search for the part of the specimen to be examined To know the proper magnification value the objective must be well fo...

Page 15: ...he whole area of the objective lens bore and enters the lens parallel to the optical axis All electron beams parallel to the optic axis are focused by the lens into a single point on the specimen surface As a con sequence the scanning is transformed into beam tilting i e the resulting pivot point of the scanning lies on the specimen surface plane The intermediate lens focuses the beam into the upp...

Page 16: ...tandard user s accounts guest supervisor Recommended centering conditions The centering is done by means of a special centering specimen which is included in the microscope accessories and is marked as ADJ The surface of this specimen has a fine structure making the centering easier If this specimen is not available it is possible to use a common specimen stub Once you start centering the image mu...

Page 17: ...ement by changing the OBJ Centering using the trackball and keys F11 and F12 DEPTH mode 1 Set the same magnification for both RESOLUTION and DEPTH modes Use the trackball 2 Set the same field of view by means of changing the IML Centering parameters using the trackball and keys F11 and F12 3 Minimize the image movement by means of changing the OBJ Centering FIELD mode 1 Set the same magnification ...

Page 18: ...acoustic contact indicator of the specimen to the chamber If contact between the specimen holder and the chamber body occurs all motorized axes will stop and an audible sound will indicate the contact touch alarm The chamber and sample stage types Type Motorized axes Manual axes Eucentricity SB X Y Rotation Z Tilt LM X Y Z Rotation Tilt automatic XM X Y Z Rotation Tilt automatic GMH X Y Z Rotation...

Page 19: ...the central vacuum tube approximately in the middle of the IML lens see chapter 4 1 Both apertures are located in the one aperture holder which is inserted in the central vacuum tube all the way down to the mechanical stop The microscope is delivered with this aperture holder inside the microscope column Low and extended low vacuum modes the same aperture holder is used as for high and medium vacu...

Page 20: ...sible to investigate both conductive and non conductive samples however non conductive samples require previous metal coating Cr Au Au Pd Pt All displaying modes are available 5 2 Medium Vacuum Mode In the medium vacuum mode up to 150 Pa it is possible to examine samples using all the displaying modes because the differential pumping aperture is located in the upper position ...

Page 21: ...ition 1 Put the low vacuum aperture 75 μm into the objective and change the aperture holder according to the description see chapter 9 5 2 2 Confirm the aperture exchange in the SEM Change UNI mode menu 3 Switch the microscope to Low vacuum mode pressure range 1 Pa 500 Pa using the UniVac button on the Low Vacuum Mode panel 4 SBU models only Close the manual valve dividing the specimen chamber and...

Page 22: ...y to material contrast of back scattered electrons The secondary electron SE detector is a basic standard detector always present in the microscope The SE detector is of Everhart Thornley type The grid on the front part of the detector has positive potential This attracts and accelerates the low energy secondary electrons arising on the specimen surface and focuses them onto the scintillator The l...

Page 23: ...tector switch off occurs Note The stability of the signal from the LVSTD depends strongly on the pressure inside the chamber In order to obtain an image with stable brightness it is necessary to have stable pressure in the chamber Therefore after a change of the required pressure value it might be necessary to wait for a while until the pressure reaches the new level and becomes stable Note The se...

Page 24: ...s a stand alone detector or exchange CL BSE detector The IR camera Chamber View must be switched off during operation of the CL detector 6 4 1 Exchange of CL for BSE lightguide Only available in exchange CL BSE of 350 650 nm range version 1 Fully retract the current detector i e it is close to the chamber wall not under the column 2 Put on gloves and open the chamber Rotate the light guide by hand...

Page 25: ...Detectors 25 VEGA 3 SEM 6 5 Other Detectors TESCAN provides other special detectors which can be attached to the microscope It is possible to obtain a list from the manufacturer ...

Page 26: ...12 hold down Blocks the changing of the left parameter of the active function 7 2 Mouse The mouse usage follows the Windows system practice Mouse functions during normal scanning Double clicking on the left mouse button on the scanning window switches the focus window on off Turning the mouse wheel changes the scan speed the scanning window needs to be active If the microscope is scanning over the...

Page 27: ...ule is active the functions of the buttons can be different 7 3 Trackball The trackball is often used with the Pad panel Turning the trackball in the direction of the axis X changes the first parameter of the active function turning the trackball in the direction of the axis Y changes the second parameter of the active function Holding the F11 key locks the first parameter of the active function u...

Page 28: ...um mode it must be conductive or must be made conductive using one of the methods described in the technical information The conductive surface of the specimen must be conductive contacted to the stub Non conductive samples can be investigated in the low vacuum mode 1 Vent the microscope by using the VENT button on the Vacuum panel Wait until the pressure is at atmospheric level 2 Set the tilt of ...

Page 29: ...n on the Vacuum panel where the actual pressure and pumping progress are also displayed Check that the chamber door is tightly closed 8 3 Images at Low Magnification There are four factory presets for the accelerating voltage 5 10 20 30 kV one for each HV index The user does not need to make any further adjustments by switching among them and using magnification up to 4000x 1 Click on the PUMP but...

Page 30: ...ge on and starts the heating of the tungsten filament see Figure 4 5 Right click in the SEM Scanning window to open the menu and select the Minimum magnification function Figure 5 6 Right click in the SEM Scanning window to select the Auto signal function to set brightness and contrast see Figure 5 Note If the Scanning window remains black select the Auto Gun Heating function using the combo box o...

Page 31: ...ble click anywhere in the SEM Scanning window 8 Focus in the Resolution mode click on the Scan Mode function in the Info Panel and select RESOLUTION or use the Continual Wide Field function 9 To select beam intensity BI 10 recommended first left click on the BI icon on the Toolbar and then use the arrows on the Pad panel Figure 7 Figure 7 10 To select the sample position on the Stage Control panel...

Page 32: ... and focused as desired right click on the Speed icon on the Toolbar and select the appropriate scanning speed 14 Clicking on the Acquire button on the Info Panel Figure 9 or on the icon on the Toolbar saves the image Fill in the note sign and description field if necessary Choose a folder in which to store the image To change the parameters of the image use the Image Parameters function in the SE...

Page 33: ... available for both modes LowVac HiVac and gives compositional information 1 Switch the microscope to Medium vacuum mode pressure range 3 Pa 150 Pa by clicking on the UniVac button on the Low Vacuum Mode panel Figure 10 In the case that even lower vacuum is needed pressure range 150 2000 Pa follow the instructions for aperture exchange in chapter 9 5 2 Enter the desired pressure value in the field...

Page 34: ...uto Signal function to set suitable brightness and contrast 9 Select the OBJ Centering function from the combo box on the Pad panel Figure 12 and turn the Trackball to set the brightest area into the centre of the Scanning window Figure 12 10 Follow the instructions 10 15 in chapter 8 3 Note Some non conductive samples which are not too sensitive to the beam can be handled at lower voltages in hig...

Page 35: ...optimum WD is about 5 mm in the case that the BSE is not mounted underneath the objective lens For BSE images the optimum WD is about 8 5 mm To change the working distance together with Z axis without defocusing the image use the WD Z function on the Stage Control panel Figure 14 Note Before changing WD Z use the degauss function by means of the icon The image should remain in focus Figure 14 7 Gr...

Page 36: ... manually click on the icon and use the Trackball 9 At higher magnifications 10 kx it is necessary to check if astigmatism Figure 17 a b is precisely corrected Figure 17 c To correct astigmatism click on the Stigmator function on the Info Panel Figure 18 For precise correction use the F11 and F12 buttons in the same way as in point 7 10 Select the appropriate scanning speed and save the image Figu...

Page 37: ... Microscope 1 Switch off the high voltage by clicking on the HV button in the Electron Beam panel 2 Close the program use Exit from the File menu select the Switch off the microscope option and exit the application 3 Wait until the VegaTC program closes itself The microscope configuration will be automatically saved on the hard drive 4 Shut down OS Windows in the usual way 5 Turn the main switch t...

Page 38: ...river size 3 2 mm general use 3 Low vacuum aperture holder with screw size M3x25 used for the removal of the low vacuum aperture holder 4 Basic specimen stubs 5 Hexagonal screwdriver size 2 5 mm used for mounting dismounting sample stage Z extensions LS LM chambers and the stub holders XM chamber 6 The distance washers 7 Aperture holder 8 Hexagonal screwdriver size 1 5 mm used for fixing the screw...

Page 39: ...vacuum hygiene during the filament exchange Dismantling and mounting of the gun is to be performed in a clean dust free environment if possible and always wearing gloves Warning Never touch the ceramic parts of the gun They function as a high voltage isolator and their surface must not become dirty it is not possible to clean the ceramic parts in any way 1 Make sure that the cathode filament is re...

Page 40: ... centered filament skip to step 15 inserting a new pre centered filament If you exchange the filament and you do not have a pre centered gun go to the next point 9 Place the Wehnelt cylinder with the filament as shown in the picture Loosen the 4 screws on the side of the Wehnelt cylinder by approximately 2 turns Use the 1 5 mm hexagonal screwdriver ...

Page 41: ...ly in the centre of the Wehnelt cylinder The filament contacts must be in line with the position pin on the Wehnelt cylinder The screws should not be fixed at this point there should be about 0 5 mm 0 02 play Note Leave the same amount of distance washers under the filament as with the previous filament In the case of using a new Wehnelt cylinder or the amount of washers used is unknown use 2 dist...

Page 42: ...gen and place the gun body back onto the column 18 Evacuate the microscope PUMP button 19 Confirm the filament exchange in the menu SEM Maintenance Confirm Filament Change This causes the reset of the filament lifetime and reset of the heating values Note Filament exchange is only allowed for Expert and higher users 9 3 Starting up the Microscope after a Filament Exchange It is necessary to perfor...

Page 43: ...e passing through the column the more electrons the better the signal from the specimen BI Typical Absorbed current Suitable range 11 230 pA 150 300 pA 20 45 nA 35 50 nA 5 If the emission current is not in the range of 60 to 90 µA it is necessary to repeat steps 1 to 10 in chapter 9 2 Filament exchange The distance washers must be removed or added and the filament centred according to steps 12 to ...

Page 44: ... set the suitable level Try to adjust the gun in alternating directions Never tighten the screws using brute force Opposite screws work against each other so in the case that one screw is fixed it is necessary to loosen the respective one 7 Once the maximum signal brightness and absorbed current is obtained fix all 4 screws uniformly to fix the gun into its position The slight drop of the signal i...

Page 45: ...ting rod and insert it in the central vacuum tube all the way down to the mechanical stop inside the central vacuum tube 6 Screw on the anode and tighten it slightly 7 Clean the gun body and the gun chamber using compressed dry air or nitrogen Place the gun on the column 8 Pump the microscope down 9 Confirm the exchange of the final aperture in the SEM Options menu check the aperture hole diameter...

Page 46: ...ted during microscope usage which can cause a decrease in the optical qualities of the column It is necessary to clean them from time to time or exchange them 9 6 Cleaning the Column Contamination on the inner vacuum surfaces of the column appears during microscope operation decreasing the optical qualities of the microscope That is why it is necessary to clean the vacuum surfaces from time to tim...

Page 47: ...strusctions below 1 Vent the microscope Vacuum panel VENT button 2 Pull the electron gun upwards remove it and place it down with the cathode upwards 3 Screw off the anode anticlockwise 4 Insert the setting rod from the delivered accessories into the central vacuum tube and lower it carefully to the aperture holder Turn the setting rod clockwise approximately one turn to screw the thread at the en...

Page 48: ...properly with clean compressed air or nitrogen after cleaning 8 Drop the cleaned or new spray aperture into the upper part of the aperture holder Check whether the aperture is oriented upwards by the bigger opening once the holder is inserted into the column the aperture will be oriented correctly with the small opening up If the aperture is not correctly oriented try to turn it by tapping the hol...

Page 49: ...ration conditions The following frequency of cleaning is recommended for usual operation Wehnelt cylinder anode according to necessity if the emission current is unstable if there is an emission current without filament heating if there are discharges of high voltage in the gun Aperture at worsened optical qualities i e if high astigmatism appears if there are major changes of the values for lens ...

Page 50: ...r of ø 20 mm Specimen holder TE0038B designed for standard ø 30 mm samples Specimen holder HM114 for flat samples up to a width of 20 mm Specimen holder GM153 replacement of the standard seven position specimen holder the seven position holder must be removed It is designed for rod shaped samples of a diameter up to 26 mm Specimen holder HM154 A CAMSCAN ø 12 5 mm specimen holder adaptor ...

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