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TEM Prep using FIB and TEM Prep using FIB and

TEM Prep using FIB and - PowerPoint Presentation

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TEM Prep using FIB and - PPT Presentation

Kleindiek MicroManipulator General Reminders Tips and Tricks When in FIB view work quickly to do what is needed and then freeze the image to avoid damage from scanning Always protect surface with ID: 383203

milling fib sample section fib milling section sample sem tem tilt view micro manipulator image grid deposition gis shown

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Slide1

TEM Prep using FIB and Kleindiek Micro-Manipulator

General Reminders, Tips and Tricks

When in FIB view, work quickly to do what is needed and then freeze the image to avoid damage from scanning

Always protect surface with

Pt

or W when using the FIB to ensure much smoother cuts

W gives the cleanest cuts since it’s more amorphous but harder to deposit

Pt

is easier to deposit but goes down as small

nano

-crystals

When at 0

o

tilt and the

eucentric

position in FIB view, it is best to have FIB Scan Rotate = 180

o

so down is down on the screen although left and right will be inverted

At 0

o

tilt and the

eucentric

position, think X & Y in the SEM view and in the FIB view think Z

GIS offset button offsets the GIS up and back for 0

o

tilt operation

Make sure the GIS offset is checked before selecting the channel (

e.g.

Channel 4 for

Pt

) when using the offset at 0

o

Always image and mill at the same current to avoid any spatial movement due to misalignment between FIB currents and apertures

Rule of thumb for depositing

Pt

is 5-6

pA

/

m

m

2

It is best to aim for 8-10 minutes/thickness in micronsSlide2

TEM Prep using FIB and Kleindiek Micro-Manipulator

Overview

e-beam deposition of

Pt

FIB deposition of

Pt

FIB milling of trapeziums

FIB “U-Cut” to create free-standing structure (except for remaining tab)

Pt

welding to micro-manipulator

FIB milling to etch remaining tab

Attaching section to TEM Grid

FIB milling to thin section to TEM thickness

Final low kV FIB milling to reduce milling damage to sectionSlide3

e-Beam Deposition of Pt

Start at 1 kV, 120 mm aperture, and high current mode

Find area of interest and set up

eucentric

and coincidence conditions

Make sure that SCM is off so that the touch alarm activates

At 0

o

tilt, make sure the GIS offset is checked and insert

Pt

Use the reduced area function and open the

Pt

valve to deposit a

Pt

strip over the feature of interest for a few minutesSlide4

FIB Deposition of Pt

Remove the GIS and tilt to 54oInsert the GIS (offset unchecked)

Select 100

pA

as the imaging current (Too high of current will cause milling rather than deposition)

In FIB view, find the area of interest and freeze the image

D

eposit

Pt

strip using conditions shown belowRule of thumb is to deposit Pt around 5-6pA/mm2 (size dependent; e.g. larger area may be half this value) and aim for 8-10 minutes/thickness in mmSlide5

FIB Milling of Trapeziums

Mill trapeziums on each side of the Pt strip at 54o using the conditions shown below

Use of XeF

2

flashing for improved etching is optional (insert XeF

2

channel and manually flash)

Conditions below are for

InAs

Harder materials (e.g. Si) may need higher milling currents (~5-10 nA)The trapezoid should extend past the Pt strip by at least 2-3 mm

At least 2-3

m

m overhang past

Pt

stripSlide6

FIB Milling of Trapeziums

InAs

Redeposition

Artifact

For the training session, we used

InAs

which is hard to mill properly

Lower FIB currents and XeF2 flashing were used to help with better milling

Below shows an example of

redeposition after our first attemptSlide7

Fine Polishing

FIB Milling of Trapeziums

Clean up the face of the trapezoi

d by etching a fine rectangle at 54.5

o

using the conditions shown belowSlide8

Fine Polishing

FIB Milling of Trapeziums

Clean up the other face of the trapezoi

d by etching a fine rectangle at 53.5

o

using the conditions shown belowSlide9

FIB Milling of the U-Cut

Go to 7o tilt and scan rotate the FIB image 180oImportant to use deposition mode (even though we are etching) so we can watch the structure break free in SEM image while the FIB milling is

occuring

Set time for 4 minutes but stop when it etches through

First CutSlide10

FIB Milling of the U-Cut

Second Cut

Remain at 7

o

tilt and scan rotate the FIB image 180

o

Important to use deposition mode (even though we are etching) so we can watch the structure break free in SEM image while the FIB milling is

occuring

Set time for 4 minutes but stop when it etches throughSlide11

FIB Milling of the U-Cut

Final Cut

Remain at 7

o

tilt and scan rotate the FIB image 180

o

Important to use deposition mode (even though we are etching) so we can watch the structure break free in SEM image while the FIB milling is

occuring

Set time for 4 minutes but stop when it etches through

Free standing structure remains except for small tab attached to the bulk of the sampleSlide12

Pt Welding to the Micro-Manipulator

Tilt to 0oUsing the camera view, bring in the

Kleindiek

probe into the vicinity of the sample stage making sure it will clear the sample height

Continue to move the probe so that it is visible in the low magnification SEM view

Make sure that the GIS offset is checked and bring in the GIS

Pt

source

Turn on the SCM so the touch alarm does not go off when bringing in the micro-manipulator probe

Lower the micro-manipulator probe such that it is about 1 mm above the sampleMove the probe to the region behind the behind the slice and centered in the trenchContinue to move down until the probe is about 500 mm above the slice, keeping it centeredOpen the

Pt valveOpening the valve causes the probe to vibrate so this must be down before the probe contacts the sampleSlide13

Pt Welding to the Micro-Manipulator

Switch to the FIB view using 20 pA to image (lower is better, but the contrast is low)

Move the sample down until it is visible in the FIB view

Align in the SEM view over the corner

Move down into contact using the FIB view (Z) and SEM (X & Y) view

Switch the FIB imaging current to 10

pA

and freeze the image

Deposit

Pt on the section and probe using the conditions shown belowNote this image has the support bar on the opposite side of where it normally is with respect to the probePt deposition should be done at 10 pA current for 6-8 minute

Checking for attachment can be done by touching the SEM table and looking at the vibration coupling in the imageSlide14

FIB Milling to Etch Remaining Tab

Use 100-200 pA FIB view imaging and a reduced area FIB image to etch away the remaining tab to the substrate to etch the section freeIt will be apparent when the section has been etched free (not shown)

Move M ↑ (stage goes down, M goes to higher values) to release the section now attached to the micro-manipulator probeSlide15

Attaching Section to TEM Grid

Remove the GIS

Go to Using camera view, remove the micro-manipulator and section to a safe location outside of the SEM stage

Move the stage to the TEM grid position and re-establish the

eucentric

and coincidence positions

At 0

o

tilt, turn SCM off and bring in the GIS

PtOpen the Pt vavle

and turn the SCM on so the stage alarm won’t go off while attaching the section to the TEM gridUsing the micromanipulator controls and the camera, SEM and FIB views, move the section into position above the TEM gridSlide16

Attaching Section to TEM Grid

Deposit

Pt

onto the grid and section and shown below

Although the recipe below is four 4 minutes, we did two steps of 6 minute depositions using 10

pA

First

Pt

Weld

1st

Pt

weldSlide17

Attaching Section to TEM Grid

Deposit

Pt

onto the grid and section and shown below

Although the recipe below is four 4 minutes, we did two steps of 6 minute depositions using 10

pA

Second

Pt

Weld

2nd

Pt

weldSlide18

Attaching Section to TEM Grid

Recipe not copied but etch using Deposition Mode, 30 kV:100

pA

, No Gas ID, Frequency X 20000, Frequency Y 1

Etch 6 minutes but stop when done

Remove micro-manipulator to safe or parked location away from stage using camera, SEM, and FIB views

Removing/Etching Away Micro-Manipulator

Etching Away Micro-ManipulatorSlide19

With the section now attached to the TEM grid, go to 54.5o stage tilt and use the FIB to thin the section using the conditions shown below

When thinning, you want to see some curtain at the bottom of the slice. This adds some additional support (This is controlled by the milling depth)

Near

end of thinning SEM beam reduced to 1 kV because sample becomes transparent at 5 kV.

The final window should be about 5 to 8 microns – sample width about 15 to 20

microns

XeF

2

flashed just

prior to final thinning on both sides of sample to clean up the In balls Sample needs to be thin, but greater than 120 nm as the thickness of the XeF2 reaction is about 60 nm thick (from previous measurements)

FIB Milling to Thin Section to TEM ThicknessFirst SideSlide20

FIB Milling to Thin Section to TEM Thickness

Tilt to 0o, perform a 180o compucentric

rotation and then tilt back up to 54.5

o

and FIB the other side using the conditions shown below

When

thinning, you want to see some curtain at the bottom of the

slice as this adds

some additional

support (This is controlled by the milling depth)Near end of thinning SEM beam reduced to 1 kV because sample becomes transparent at 5 kV.The final window should be about 5 to 8 microns – sample width about 15 to 20 micronsLook for the Pt receding to the top of the sample in

SEM view while milling as this is the indicator to stop (final endpoint)Watch for uneven recession – our sample bowed and the two ends receded before the middle

Second SideSlide21

Final Low kV FIB Milling to Reduce Milling Damage to Section

Tilt sample to 45o and use low kV (5 kV: 100 pA) final polishing in deposition mode for 10-60 seconds on each side

Time needed is sample dependent (TEM imaging is ultimate test)

Final polishing is being done on the opposite side from the SEM view so cannot monitor progress but can see punch through