Tescan MIRA3 User manual

The reproduction, transmission or use of this document or its contents is not permitted without 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.
© 2013 TESCAN, a.s., Brno, Czech Republic

Contents
1
MIRA3
FEG
-
SEM
Contents
Contents ........................................................................................................................... 1
1 Introduction ............................................................................................................... 3
2 Safety Information ...................................................................................................... 4
3 Installation and Microscope Repairs ............................................................................ 5
3.1 Transport and Storage .............................................................................................. 5
3.2 Installation Instructions ............................................................................................ 5
3.3 Fuse Replacement ..................................................................................................... 5
3.4 Instrument Repair and the Spare Parts Usage ............................................................ 5
4 Description of the Microscope .................................................................................... 6
4.1 Electron Column ....................................................................................................... 6
4.1.1 Electron Column Displaying Modes................................................................... 9
4.1.2 Electron Column Centering ............................................................................. 14
4.1.2.1 Centering of the Electron Gun ..................................................................... 14
4.1.2.2 Automatic Centering ................................................................................... 15
4.1.2.3 Manual Centering ........................................................................................ 15
4.1.2.4 Electron Column Precentering ..................................................................... 16
4.1.3 Angular Intensity Calibration .......................................................................... 17
4.2 Chamber and Sample Stage .................................................................................... 20
5 Vacuum Modes ........................................................................................................ 21
5.1 High Vacuum Mode ................................................................................................. 21
5.2 Low Vacuum Mode .................................................................................................. 21
6 Detectors ................................................................................................................. 22
6.1 SE Detector ............................................................................................................. 22
6.2 In-Beam SE Detector ............................................................................................... 22
6.3 LVSTD Detector ....................................................................................................... 23
6.4 BSE Detector ........................................................................................................... 24
6.5 CL Detector ............................................................................................................. 24
6.5.1 Exchange of CL for BSE Lightguide ................................................................. 24
6.6 Other Detectors ...................................................................................................... 25
7 Control Elements ...................................................................................................... 26
7.1 Keyboard ................................................................................................................ 26
7.2 Mouse ..................................................................................................................... 26
7.3 Trackball ................................................................................................................. 27

Contents
2
MIRA3 FEG
-
SEM
7.4 Control Panel .......................................................................................................... 27
8 Getting Started ......................................................................................................... 28
8.1 Microscope Starting ................................................................................................ 28
8.2 Specimen Exchange ................................................................................................ 29
8.3 Images at Low Magnification ................................................................................... 30
8.4 Imaging in Low Vacuum Mode ................................................................................ 33
8.5 Images at High Magnification .................................................................................. 35
8.6 Electron Beam Lithography ..................................................................................... 38
8.7 Microscope Stopping .............................................................................................. 43
9 Microscope Maintenance .......................................................................................... 44
9.1 Basic Microscope Accessories ................................................................................. 44
9.2 Insertion of the Final Aperture for the Low Vacuum Mode ...................................... 45
9.3 Cleaning of the Final Aperture ................................................................................ 45
9.4 Specimen Holders ................................................................................................... 46

Introduction
3
MIRA3
FEG
-
SEM
1 Introduction
The MIRA3 series is a family of high-quality; fully PC-controlled scanning electron
microscopes equipped with a Schottky Field Emission electron gun designed for high vacuum
or variable pressure operations.
The most important features of the microscope are:
 High brightness Schottky emitter for high-resolution/high-current/low-noise
imaging.
 Unique three-lens Wide Field OpticsTM design offering the variety of working and
displaying modes embodying the Tescan proprietary Intermediate Lens for the beam
aperture optimization.
 Real time In-Flight Beam TracingTM for the performance and spot optimization
integrating the well established software Electron Optical Design .
 A powerful In-Beam detector of secondary electrons located in the objective lens
enabling work at very short working distances for high resolution.
 Fast imaging rate.
 High-throughput large-area automation, e.g., automated particle location and
analysis.
 Fully automated microscope set-up including electron optics set-up and alignment.
 Sophisticated software for SEM control, image acquisition, archiving, processing and
analysis.
 Network operations and built-in remote access/diagnostics.
This manual provides an overview of the components, the operational principles and the use
of MIRA3 scanning electron microscopes. Not all parts of this manual may apply to a given
installation nor should be taken laterally in all cases. Details of the MiraTC software may also
vary according to the actual setting and thereby differ slightly from what is shown in the
figures.
Since MIRA3 is installed and maintained by trained specialists, technical details and
installation procedures are limited to a short overview. In case of necessary maintenance,
reinstallation, hardware changes, etc. the appropriate service authorities or your local
supplier must be contacted for further assistance and instructions.

Safety Information
4
MIRA3 FEG
-
SEM
2 Safety Information
The microscope is equipped with an uninterruptible power supply (UPS). The following steps
are necessary to remove voltage from all the parts of the microscope:
1. Unplug the mains power cord of the UPS from the mains socket.
2. Switch the mains switch of the UPS to the off position.
Only a service engineer can perform operations with the microscope mains switch, UPS
mains power cord or UPS mains switch.
The user is liable to make himself familiar with the care of the device and with the safety
rules valid in the country of the user. The microscope works with electric voltages that can
be dangerous to life.
Any operations with the device which are not mentioned in these instructions, especially the
removal of the housing and manipulation with the electric parts of the microscope, may be
carried out only by an authorized person. It is also forbidden to substitute a part of the
microscope for any other part that is not original and is not delivered by the microscope
producer (e.g. the substitution of the original steel blinds on the flanges of the microscope
chamber for light alloy blinds can cause an emission of dangerous ionizing radiation!)
The microscope is provided with a number of automatic protections making unsuitable use
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 and endanger of the
health of the operating staff.
The symbols used meet the regulation standard ČSN EN 61010-1, except the symbol
, marking the connectors with high voltage that are not dangerous in aspect of the mentioned
regulation standard (accidental touch can only cause electrical shock).
In the documentation there will two type of additional information given: Notes and
Warnings,
Notes are designated thus: Note:
In Italics and Blue print.
Warnings are designated thus: WARNING:
In Italics and Red print.

Installation and Microscope Repairs
5
MIRA3
FEG
-
SEM
3 Installation and Microscope Repairs
3.1 Transport and Storage
The method of delivery is defined in the contract and it is determined individually according
to the destination territory. The method of delivery must be approved by the manufacturer.
The instrument is delivered partially disassembled and packed. The purchaser is obliged
to check the status of the boxes after handover by the delivery company. In the case of any
damage it is necessary to catalogue the damage and inform the manufacturer of the
situation. The packed instrument must be stored in a dry and clean place with a temperature
range from -20 °C to +40 °C and must not be exposed to corrosive substances which can
cause oxidation (acid vapours etc.).
3.2 Installation Instructions
The microscope is delivered including installation. Installation must be ordered from the
seller. The customer shall inform the seller of the readiness of the laboratory for the
installation. Once the laboratory 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 start from this date and
the user can start using the instrument normally as described in this manual.
3.3 Fuse Replacement
The instrument does not contain any fuses which can be replaced by the user. All fuses are
located under the covers, which can be removed only by a service technician from the
manufacturer or a service technician of an approved company. The fuses can be replaced
only by exactly the same type; the type is described in the documentation or on the fuse
holder.
3.4 Instrument Repair and the Spare Parts Usage
It is only permitted to use original spare parts delivered by the manufacturer. Repair and
maintenance which exceed the procedures mentioned in this manual can be performed only
by the manufacturer’s service technician or a service technician from an approved company.

Description of the Microscope
6
MIRA3 FEG
-
SEM
4 Description of the Microscope
4.1 Electron Column
The scanning electron microscope displays the examined object by means of a thin electron
probe. The column forms the electron probe (beam) and sweeps the beam over the
examined specimen located in the microscope chamber. Most imaging qualities of the
microscope depend on the parameters of this electron beam: spot size , aperture angle and
beam intensity .
The spot size determines the resolution of the microscope as well as usable magnification
at stable picture sharpness. It is mainly considered that the spot is circular and has
a Gaussian intensity profile. We can specify its size for example with half the width of the
intensity distribution. The spot size is determined by the demagnification of the primary
electron source, optical aberrations of the final lens (objective) and the diffraction aberration
on the final aperture. The spot size is smaller at shorter working distances.
The incident electron beam is cone-shaped. The vertex angle of the cone is determined
by the aperture angle. The wider the cone, the lower the depth of focus.
The beam intensity (BI) is determined by 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 evident that the incident beam parameters influence each other. The optical system
of the microscope allows operation in different modes when some parameters of the beam
can be preferred and the others can be kept down. Here are some typical examples:
 Work at high magnification . It is necessary to reach a high resolution; therefore a low
beam intensity, short working distance and slow scanning speed should be used. We
recommend using RESOLUTION mode, working distance not more than 7 mm and
scanning speed 7 or slower. See chapter 4.1.1.
 Work with high intensity . Resolution is small and useful magnification is low but fast
scanning can be used because the signal to noise ratio is better. In any mode, use the
function BI. The higher the BI index, the higher the beam intensity (the current
of electrons in the beam). The exact value of the intensity can be set by function BI
continually.
 Work with high depth of focus . The aperture angle must be small. Use DEPTH mode.
The column of the MIRA3 microscope consists of the following main parts:
 The electron gun is the source of accelerated electrons. It consists of a suppressor,
an extractor and an anode. The filament tip is connected to the negative electric
potential while the anode is on zero potential. The filament tip is made of a tungsten
wire with about 0.5 µm radius sharp peak. The filament tip is fixed to the tungsten
wire heated to a temperature of 1800 K. Electrons are emitted by the tunneling
through the surface barrier with contribution of the strong electrostatic field with
an intensity of 108 V/m (Schottky effect).
The tip’s high temperature helps to prevent contamination of the tip and together
with an atomic layer of the ZrO on the surface helps improve conditions for electron
emission. The extractor ensures a high electrostatic field on the filament tip. It is

Description of the Microscope
7
MIRA3
FEG
-
SEM
located right in front of the filament tip and it has a positive voltage potential
of several kilovolts (extracting voltage).
The MIRA3 cross-section and schematic representation of its optical elements:
The electron flow from the gun is specified by the emission current , which depends
on the extracting voltage. Electron emission from the side of the filament is
suppressed by the suppressor, which is located right behind the filament tip. The
suppressor potential is several hundreds of volts lower than the filament tip
potential. The accelerating voltage between the cathode and the anode determines
the overall energy of the electrons.
The whole system behaves as an electron virtual source located in the region of the
end of the tip with a characteristic size of approximately 20 nm, energy of the
electrons in the range from 200 eV to 30 keV and emission current up to 300 µA.
An important parameter of the gun is the angular intensity of the electron emission
which depends mainly on the extractor voltage. The value of this parameter is
important for electron emitter lifetime, therefore the angular intensity must be
calibrated if necessary (see chapter 4.1.3). The angular intensity is also used for

Description of the Microscope
8
MIRA3 FEG
-
SEM
precise calculation of the beam current on the sample. The In-Flight Beam Tracing
procedure is utilized in this calculation.
 The condenser C1 is a strong magnetic lens which controls the amount of electrons
passing through the aperture diaphragm. The higher the condenser excitation, the
shorter the focal distance and thus the beam cross-over is further from the aperture
diaphragm. By moving the cross-over towards the aperture diaphragm the beam
current becomes higher. The condenser current and thus its focal length can be
controlled by means of preset BI (Beam Intensity, BI 1 - BI 20) steps, or by entering
the direct beam current value (BI Continual) or by the spot size value (Spot Size)
which is strictly related to the beam current.
 The gun centering is formed by a system of electromagnetic deflection coils under
the gun. It is intended for tilting the electron beam emitted from the gun, so that it
enters the axis of the optical system of the column. It is controlled by the Gun Tilt
function. The gun can be centered optimally by the automatic function which can be
activated by the Adjustment >>> Auto Gun Centering button.
 The fixed aperture diaphragm trims the final displaying beam. It is located under the
condenser and gun centering coils. The size of the diaphragm is chosen according
to the optimal aperture angle of the electron beam and determines the maximum
resolution ability of the column.
 The auxiliary IML lens is a magnetic lens used for the aperture change of the beam
entering the objective lens or for beam displaying if the objective lens is off. The
change of the IML excitation causes a shifting of the electron beam across the optical
axis and it is therefore necessary to compensate this shifting by means of the
centering coils IML Centering.
 The stigmator is an electromagnetic with an octupole design. It is intended for
compensation of astigmatism in all displaying modes.
 The scanning coils are formed by two stages of the deflection coils. A scanning ramp
is connected to the coils. The ramp frequency determines the scanning speed of the
electron beam; the amplitude determines the microscope's field of view and the
magnification.
 The objective is the last magnetic lens of the column that forms the resulting
electron beam. In the usual modes the excitation of the OBJ determines the working
distance - the distance between the focused specimen surface and the lower
objective pole piece. In the MIRA3 with In-Beam technology the lens is combined
electrostatic-magnetic for further improvement in microscope performance.

Description of the Microscope
9
MIRA3
FEG
-
SEM
4.1.1 Electron Column Displaying Modes
RESOLUTION Mode
This is the basic and most common displaying mode. The IML lens is switched off, the OBJ
lens is excited and it focuses the final electron beam.
Characteristic:
 high resolution
 low depth of focus
The MIRA3 works like the other common three lens microscopes
without IML in this mode. 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 objective OBJ is performed by defined beam
tilt of the central electron beam, which does not cause image shift.
This mode is intended for displaying with the highest resolution.

Description of the Microscope
10
MIRA3 FEG
-
SEM
DEPTH Mode
The DEPTH mode differs from the previous mode by the 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 RESOLUTION mode. The beam in the probe
stays unchanged. This mode is used if necessary to have a greater
depth of focus.

Description of the Microscope
11
MIRA3
FEG
-
SEM
FIELD Mode
The FIELD mode utilizes the intermediate lens IML for the electron beam focusing while the
objective OBJ is off.
Characteristics:
 large field of view
 high depth of focus
 worse resolution
The beam aperture is very small and the depth of focus is usually
higher than the field of view. As the objective OBJ is off in this case,
it does not affect the middle 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 RESOLUTION mode to FIELD mode.
The disadvantage of this mode is a bigger spot size; the maximum
magnification used is a few thousand. The mode is used for the
searching of the parts of the specimen to be examined.

Description of the Microscope
12
MIRA3 FEG
-
SEM
WIDE FIELD Mode
The WIDE FIELD mode uses the intermediate lens IML for focusing the electron beam, while
the objective OBJ is excited to a high value.
Characteristics:
 extra large field of view
 image distortion is corrected and minimized
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 focused. This might be a little difficult due to the high
depth of focus.

Description of the Microscope
13
MIRA3
FEG
-
SEM
CHANNELING Mode
In CHANNELING mode, the scanning and lens focusing is controlled so that the electron
beam touches the same point of the specimen surface all the time. By means of scanning the
beam, only the angle of incidence of the electron beam is changed, i.e. the rocking beam.
Characteristics:
 the position of the specified point in the image depends
on the beam tilt
 it is the mode for ECP acquisition - Electron Channeling
Pattern
The resulting image is the amount of electrons dependent on the
impacting beam angle. The excitation ratio of the scanning coils is
set up so that the beam utilizes the 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 consequence, 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 upper focal point
of the objective lens. The result is that the beam, after passing
through the objective lens, is parallel and the angular resolution
of ECP (Electron Channeling Pattern) images is at its maximum.
The mode is intended for the examination of crystallographic
materials. In consideration of the optical abilities of the MIRA3
column, the minimum size of crystals is (100–150) µm.
Note: ECP patterns are produced by back scattered electrons, it is preferable to use a BSE
detector for imaging if available.

Description of the Microscope
14
MIRA3 FEG
-
SEM
4.1.2 Electron Column Centering
To reach high quality images it is necessary to center the electron optics of the column. The
centering is electronic and fully controlled by the PC.
Each microscope is factory centered and this setup is stored in the Default configuration. By
using the Load Default Configuration function from the menu Options -> Configurations ►
the user will save time in the case he gets lost, loses his configuration completely etc. This
default configuration file is also used when a new user is created as his initial configuration.
There are factory presets for four accelerating voltages, one for each HV index (see the table
on page 16). Switching among them the MiraTC software remembers all settings so the user
does not need to make any further adjustments. However, changing the voltage within
a single HV index requires performing the centering of the microscope:
1. centering of the gun (see chapter 4.1.2.1);
2. centering of the column, either automatic (see chapter 4.1.2.2) or manual (see
chapter 4.1.2.3) for work at high magnifications.
Note: Every user can save his own configurations in menu Options -> Configurations ►. Save
as. Using of various configurations can save user’s time when switching between various
voltages within the same HV index.
Recommended centering conditions
The centering is always 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 clean common specimen stub. Once you start centering, the image must be focused
perfectly.
Mode Working Distance (WD) Beam Intensity (BI) Magnification (Mag)
RESOLUTION
Current WD on what you
want to acquire images
Current BI on what you
want to acquire images (2000–5000)x
DEPTH Current WD Current BI 2000x
FIELD Current WD Current BI 500x
WIDE FIELD Current WD Current BI max. Mag
4.1.2.1 Centering of the Electron Gun
The centering is done by automatic procedure. It is always necessary to perform this auto
centering in each HV index which is used. Use HV according to the table on page 17.
1. Insert the centering specimen.
2. Focus the image in RESOLUTION mode and then set up minimum magnification (use
WD approximately 5 mm or any preferable WD).

Description of the Microscope
15
MIRA3
FEG
-
SEM
Figure 1
3. Use the Adjustment >>> Auto Gun Centering function in the Electron Beam panel
(Figure 1).
4.1.2.2 Automatic Centering
The automatic procedure of column centering is very fast and suitable for low
magnifications. For very precise work at high magnifications the manual centering is more
suitable (see chapter 4.1.2.3).
1. Insert the centering specimen.
2. Set up the recommended working conditions and focus the image in RESOLUTION
mode.
3. Use the Adjustment >>> Auto Column Centering function in the Electron Beam panel
(see Figure 1).
4.1.2.3 Manual Centering
1. Insert the centering specimen.
2. Set up the recommended working conditions and focus the image in RESOLUTION
mode.
Note: Manual centering is for experienced users and it is necessary to perform it individually
for each from four HV indexes and keep to described sequence for each procedure. The
RESOLUTION mode must always be adjusted first.
Note: If working at a higher magnification and precise centering is needed, the manual
centering procedure should first be done at a lower magnification and repeated more
precisely at higher magnification.
Note: In the case of MIRA3 with InBeam detector check the item InBeam Mode in the main
SEM menu.
3. Use the Adjustment >>> Manual Column Centering function in the Electron Beam
panel (see chapter 8.5). Press Next>> button. The image starts wobbling, that is,
periodically changing the working distance.
4. Minimize the image movement by changing the OBJ Centering (select in the Pad
panel) using the trackball and F11 and F12 keys. Press the Finish button.
It might also be necessary to have FIELD or DEPTH modes precisely centered if working
at higher magnifications. If needed proceed with the following steps:
5. Switch to FIELD mode. Set the same magnification for RESOLUTION and FIELD modes.
Use the Adjustment >>> Manual Column Centering function in the Electron Beam

Description of the Microscope
16
MIRA3 FEG
-
SEM
panel. Press Next>> button. Minimize the image movement by changing the IML
Centering (select in the Pad panel) using the trackball and the F11 and F12 keys.
Press Next>> button. Adjust the OBJ Centering so that the image is the same
as in RESOLUTION mode (use the trackball and the F11 and F12 keys). Press the
Finish button.
6. Switch to DEPTH mode. Use again the procedure with Manual Column Centering and
OBJ Centering (steps 3. and 4.).
7. Switch to WIDE FIELD mode and set the same magnification for RESOLUTION and
WIDE FIELD modes. Use the Adjustment >>> Manual Column Centering function
in the Electron Beam panel. Press Next>> button. Adjust the OBJ Centering so that
the image is the same as in RESOLUTION mode (use the trackball and the F11 and
F12 keys). Press the Finish button.
MIRA3 with InBeam detector:
It is recommended to work with enabled InBeam mode all the time. However, there is the
possibility to use purely magnetic objective lens. Proceed with following:
1. Uncheck the item InBeam Mode in the main SEM menu.
2. Select the SE detector in the SEM Detectors & Mixer panel.
3. Switch to RESOLUTION mode and center the mode as usual. Ensure that the image is
correctly stigmated; especially at low accelerating voltages (it is applicable also for
other modes).
Note: If the InBeam mode is switched on/off, it is recommended to carry out the centering
of the electron column again.
It might also be necessary to have FIELD or DEPTH modes precisely centered if working
at higher magnifications. If needed proceed as follows:
4. Switch to DEPTH mode and centre this mode as usual.
5. Switch to FIELD mode and only set the same field of view by changing the OBJ
Centering.
6. Switch to WIDE FIELD mode and center this mode as usual.
7. Repeat steps from 3. to 6. for each of four HV indexes.
Note: If you want to align field of view for DEPTH mode exactly with RESOLUTION mode (for
magnifications > ~10kx), set the same magnification in RESOLUTION and DEPTH modes and
then set the same field of view by means of changing the IML Centering parameter.
4.1.2.4 Electron Column Precentering
The column is factory precentered. It is also precentered after every filament exchange
by the service technician. Further precentering can be performed only by an Expert level
user. This can be an advantage at lower accelerating voltages (HV < 5 kV). On the other
hand, incorrect precentering can cause a situation where the objective and stigmators cannot
be corrected at all.
WARNING: This procedure has a strong influence on the other centering parameters and thus
is recommended only for experienced user.

Description of the Microscope
17
MIRA3
FEG
-
SEM
There are four HV indexes, which should be precentered with care:
HV index Range of beam voltage [kV] Beam voltage for centering [kV]
1 0–3 2
2 3-7 5
3 7-15 10
4 15-30 20
Instructions:
1. Set the HV index and the correct HV for precentering according to the preceding
table and change the scanning mode to RESOLUTION. Set the values of Stigmators,
IML centering and OBJ centering in the Pad panel to 0 %.
2. Focus the image on the centering sample at magnification >> 1kx (for example 4kx).
3. Use Manual Column Centering and check the option Use OBJ Precentering.
4. Press Next>> button and minimize the image movement with the OBJ Precentering.
5. Press the Finish button.
6. Switch to FIELD mode and center this mode (follow the wizard).
7. Switch to RESOLUTION mode, focus and centre the mode as usual (not checking the
option OBJ Precentering).
8. Center the stigmators: use the Stigmator A/B Centering function in the main SEM
menu and follow the wizard for Stigmator A and Stigmator B (use trackball).
9. Switch to DEPTH mode, focus and centre this mode (follow the wizard).
10. Switch to WIDE FIELD mode and centre this mode (follow the wizard).
11. Repeat steps from 1. to 10. for each of four HV indexes.
Note: In case of MIRA3 with InBeam detector, check the item InBeam Mode in the main SEM
menu. If it is necessary to work with disabled InBeam mode, follow the part MIRA3 with
InBeam detector in the chapter 4.1.2.3.
4.1.3 Angular Intensity Calibration
The lifetime of the electron emitter (in the electron gun) depends on the operating
conditions, especially on the extractor and suppressor voltage and filament current. These
parameters have to be set carefully so that the value of angular intensity ranges from
0.20 mA/srad to 0.27 mA/srad. Additionally, the angular intensity influences the accuracy
of In-Flight Beam Tracing calculations.
Note: This procedure can be performed only by a user at supervisor level.
Instructions:
1. Set the accelerating voltage (HV) to 5 kV and beam intensity (BI) to 10 (see chapter 8).
2. Turn the electron beam on.

Description of the Microscope
18
MIRA3 FEG
-
SEM
3. Perform the gun, column and stigmators centering (see chapter 4.1.2.1 and 8.5). Use
RESOLUTION mode and the SE detector.
4. Focus the electron beam on an edge of the Faraday cup (conductive cup designed for
electric charge capture in a vacuum, see the figure above) on the sample stage. Use
a WD of between 5 mm to 20 mm. Then direct the beam into the above-mentioned
Faraday cup and set the magnification to a level that makes the field of view smaller
than the shape of the cup (you should see a black live image). You can also use the
small Focus window inside the Faraday cup. Each Tescan carousel is equipped with
at least two Faraday cups.
Figure 2
1. Focus on the edge properly.
2. Point the whole beam
in
the Faraday cup.
Faraday
cups