Handbook Of Strata 235 Dual-beam Sem, Fib Electron Microscope

Handbook of precautions, basic functions and features of the “DualBeam Strata 235 SEM-FIB electron microscope”

Name:

Nauman Mithani (Chemistry major)

Professor:

Dr. Karen Kavanagh (Nano-imaging, Physics)

Date:

April 21st, 2007

Term:

1071 (January - April 2007)

Object:

Co-op work term report

Title:

Handbook of precautions, basic functions and features of the “DualBeam Strata 235 SEM-FIB electron microscope”

i

Contents

●

General information........................................................................................................................................................................................................pg ii

●

Chapter 1: Precautions and conditions...........................................................................................................................................................................pg 1

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Chapter 2: Starting procedures.......................................................................................................................................................................................pg 2

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Chapter 3: Imaging chapter 3.1: Commencement and the first images............................................................................................................................................pg 4 chapter 3.2: Image adjustment and optimisation...............................................................................................................................................pg 5 chapter 3.3: Free analysis of the sample...........................................................................................................................................................pg 7

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Chapter 4: 'EDX' mode (determination of elemental composition)..................................................................................................................................pg 9

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Chapter 5: 'FIB' mode (milling and etching of arrays or patterns) chapter 5.1: Preparation....................................................................................................................................................................................pg 13 chapter 5.2: Application 1: milling custom patterns...........................................................................................................................................pg 18 chapter 5.3: Application 2: measurement of height, depth or thickness............................................................................................................pg 19

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Chapter 6: End of session..............................................................................................................................................................................................pg 20

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Bibliography....................................................................................................................................................................................................................pg 21

ii

General information Disclaimer:

This is to serve as a handbook of reminders and is by no stretch of the imagination the definitive collection of instructions for the operation of this instrument. The science behind this electron microscope, micro and sub-micro scale imaging is to be sought elsewhere. Initial training, introduction and familiarisation must be provided by the supervisor.

Universal rules:

Always be gentle, in all aspects of operation of the instrument (the further the size of an object from that of an every-day object, the rarer, more sensitive and expensive it is).

Key:●

{?} represents a physical button e.g. {Off} means a physical 'Off' button on a panel somewhere.

●

[?] represents a button, feature or drop-down menu in a software e.g. [Vent] means the 'Vent' button/feature/option in the software that may be accessed by clicking on it using the mouse

●

((?)) represents a physical knob.

●

Screenshots of the software, its functions and features may be consulted in the official “Reference Guide”.

●

Preferably, the user should save the transfer images of the sample analysis in a personal USB drive or removable device. Once a

Recommendations:

particular project or experiment is concluded, all pertinent data should be removed from both computers (a procedure is stated in box no. 31.2).

1

Chapter 1: Precautions and conditions #

Precaution/Intention

Suggestion/Method

Additional notes, comments

Any foreign substance in the main chamber is a contamination. If a thread falls on the sample, to say the 1

Laboratory apparel

Do not wear clothes with loose threads.

least, the user may obtain undesirable images. If a thread falls between the chamber door and the chamber wall, the essential vacuum shall not occur due to an incomplete seal.

2

... and the hair

Use Rubber-bands, hair-bands, fellow user's hands etc. to keep them from the sample. The sample must be clean, dry and must not be

3

Sample condition

something that may out-gas significantly; it must not be a magnetic substance. These conditions are to be met in the sample preparation.

4

Sample preparation

5

Handling the sample

As above.

The electron beam must reach the sample un-interrupted. Secondly, a magnetic substance may bend/deflect the electron beam.

Please use another, appropriate laboratory other than the The Nano-imaging Facility wishes to avoid any lingering Nano-imaging Facility.

odours or spills.

Wear nitrile or latex gloves.

Minimising sample contamination.

These are physical, translucent buttons, located on a Check the {STBY}, {OFF}, 6

panel before the stage motion joystick. Check (but do not

{Vacuum}, {High Tension} and touch) that the {STBY}, {OFF}, {Vacuum}, {High Tension} {ON} lighted switches

buttons are lit, and the dark green {ON} button is not lit. If not, the supervisor is to be alerted immediately.

The instrument shall not function properly or at all. So, do not

proceed.

2

Chapter 2: Starting procedures #

Precaution/Intention

Suggestion/Method

Additional notes, comments The computer hosting the main FEI xP analysis software is

7

The primary electron microscope computer.

Press {1} on the 'Raritan Compuswitch' box on top of

aged in every sense of the word. Hard-drive, memory and

the ultra-sensitive (pico) ammeters.

processor speed are limited, so anything and everything that that can be hosted by another computer is.

8

User log-in

[File] menu then [User login]

This is to maintain a trace of usage per user.

[Pages] menu in the top-right corner of the screen,

9

Reset the sample stage position.

select the [Work] page and set the [X], [Y], [Z], [T] (tilt)

This is done to start the analysis from the zero (default)

values to zero; location is near the centre of the page.

position. The zero or (for that matter) any position is relative

Do press enter in each box when the values are put in

to the sample stage. Unfortunately, there is no way to ensure

to register them. If 'Z' is not available, select [Unlink Z

a particular position of the sample stage corresponds exactly

from FWD] from the [Stage] menu.

to a particular point on the sample every time it is loaded.

Do not set FWD to zero. Vent the main chamber 10

(equalise the internal pressure with that of the outside).

[Pages] menu in the top-right corner of the screen, select the [Startup] page then click on [Vent].

Venting shall take up to five minutes approximately. 11

Opening the chamber door

Pull gently at the chamber door's horizontal bar; if the door slides open then venting has concluded, otherwise not.

In order to equalise the pressure, the chamber is flooded with inert, gaseous nitrogen. Recall, air, due to its moisture content, cannot be used. To allow the user to place the sample onto the stage in the chamber. If the chamber door does not budge at the slight pull, there is yet significant pressure difference with the outside.

Do not pull with force.

3

#

Precaution/Intention

Suggestion/Method

Additional notes, comments

With covered hands, place the sample onto the stage, 12

Mounting the sample

then fix its position by inserting the hex-screw provided An uncontaminated sample is securely placed onto the in the hole below the sample holding stage's surface

sample holding stage.

and turning clockwise. With the help of a particular tool (the height gauge, for lack of a better name) provided in the same box as the 13

Height check

hex-screw, check the height of the sample. If as high or higher than the limit denoted on the tool, consult the

If the sample is too high, it would clash with the detector(s) or the tip(s) of the electron/ion column(s).

supervisor. Gently push the chamber door to close the chamber. Go to the [Startup] page and initialise the vacuum by 14

Re-establishing vacuum

accessing the [Pump] feature. A box may appear with further vacuum related options, click [OK]. Physically, keep the chamber door pressed

This is the procedure for establishing vacuum. The push is for facilitating a difference in air pressures to “grab” and seal the door.

at the spot where it says, for approx. a minute.

15

Maximum working pressure (air)

On the [Startup] page, towards the bottom, is an numerical indicator of the “chamber pressure”, wait until it is falls to 3.0×10-5 milli-bar.

The maximum (air) pressure is simply a working vacuum limitation of the instrument.

4

Chapter 3: Imaging chapter 3.1: Commencement and the first images #

16

17

Precaution/Intention

Commencement: applying the 'High Voltage'

'Detector' check

Suggestion/Method

Turn on the [HV] feature in the “Electron Column” section on the [Startup] page. Select, if not selected by default, [SED] from the

[Detector] menu.

Additional notes, comments Turns on the electron beam (E-Beam) and engages the accelerating voltage to apply the driving force for the electrons. This is the standard detector mode; its selection is deliberate. When there may be a need to raise the accelerating voltage

18

'E-Beam' HV check (High Voltage)

To start with, select [5 kV] from the [E-Beam] menu to

(e.g. when conducting analysis of elemental composition),

apply the driving force for the electrons. Most probably, raising it too high could cause the sample to become charged it shall be selected by default.

resulting in distorted/shifting images. The visible effect of a change is in the contrast of the image.

To select the 'search' mode, [E-Beam] menu → 19

E-Beam mode: SRH (Search)

[Imaging Mode] sub-menu → [Search]. This is the default mode.

This is the “general purpose” mode. The other modes serve more specific purposes and thus have more limitations.

Access the [Set Continuous Scan] function from the

20

Inaugural image acquisition

[Scan] menu, then select the resolution. Start with a

Thus, the user obtains the very first image(s) of the day.

lower ‘Resolution’ such as [0.181] . If scanning does

The 'resolution' is the image update-time. The image(s),

not commence, access the [Start Scan] function or

understandably, would hardly be of any use since the settings

press {F6} on the keyboard. This and the [Start Scan]

of contrast, brightness and focus would not be optimised.

function start/resume the continuous scanning.

5

Chapter 3.2: Image adjustment and optimisation #

Precaution/Intention “E-Beam Link Focus”:-

21

linking 'Z' to 'FWD (Free Working Distance)'

Suggestion/Method

A box may appear on the screen asking to link 'Z' and 'FWD' which is not be answered for the time being. The box may be put aside but do not answer it. The

Brightness and contrast

'Z' and 'FWD' represent the height and distance of the sample stage relative to the beam sources respectively (e.g. the electron beam gun). Eventually, when the beam has been focused, [OK] may be pressed.

button in the toolbar below the menus may be used to execute the initial auto adjustment of

22

Additional notes, comments

brightness and contrast. Adjust the ((Brightness)) and ((Contrast)) on the panel before the keyboard in order to fine tune the brightness

Once these subjective parameters have been set, a sufficient contrast between the background and surface topography obtained, the user may move on to 'focus'.

and contrast of the image. The user may zoom out using the central An appropriate spot:23

choosing a point for the initial focus

((Magnification)) dial. One way is to use the creamcoloured joystick to the left of the panel, whilst the alternative is to double-click on the spot on the screen which one wishes to bring to the centre. The electron beam may be shifted using the ((X)) and ((Y)) knobs on the same panel that bears the ((Magnification)) dial.

One wishes to bring to the viewing area, a rugged region of the sample, one with peaks or variations in topography. Naturally, it would be awkward to bring anything into focus over a flat, unchanging, planar region. The ((X)) and ((Y)) knobs may be used for fine movements. Remember, these knobs shift the electron beam, not the sample stage.

6

Then, set the magnification to at least '1000X', this may be done by using the ((Magnification)) dial; or 24

Focus

typing '1000' in the box containing the magnification value on the [Work] page. Adjust the focus of the image by the ((Coarse)) and ((Fine)) focus knobs.

The '1000X' magnification value is a reasonable starting point for initial focusing. If the user intends to conduct imaging at only higher magnifications then initial focusing may be carried out at a higher magnification. Focus, akin to decimal place accuracy, is more accurate if carried out at a higher magnification. In a manner of speaking, a calibration has been conducted.

25

Response to the 'EBeam Confirm Focus' box

Once the image has been focused, answer the box by

As per the official statement, “...sample collision protection...”

clicking [OK]. If the 'E-Beam Link Focus box' was

has been set. Now, 'Z' on the [Work] page has become

[Cancel]led then 'Z' may be linked to 'FWD' by pressing 'FWD'. Remember, a change in the focus shall cause a the [Z=FWD] button on the [Work] page.

change in the FWD (a numerical indication) value and so one may freely adjust the focus.

((X)) and ((Y)) stigmator knobs may be used to adjust 26

Stigmator controls (Advanced)

By far, the most challenging parameter in image adjustment.

astigmatism. If before/during focus, the image seems to In the beginning, it is advised to adjust only one knob at a shift or blur in a particular direction, and if after

time and carefully at that. Astigmatism is many a time the

focusing, the image seems to be blurred in a particular

culprit in skewed milled patterns (Ion beam mode). There is

direction, astigmatism shall have to be adjusted.

no numerical value associated with the stigmator controls.

7

Chapter 3.3: Free analysis of the sample #

Precaution/Intention

Suggestion/Method

Additional notes, comments

The sample stage may be subjected to translational Translational movement 27

movement by using the cream-coloured joystick to the

(viewing other areas and points left of the panel, whilst an alternative is to double-click on the sample)

on the spot on the screen which one wishes to bring to the centre. Resumption of scanning removes the image originally present in the quadrant and scans the area under viewing in the

28

Screen quadrants (NOTICE)

One may switch to another quadrant by a mouse-click.

former active quadrant, and NOT the area originally

Switching quadrants 'freezes' scanning.

displayed in the quadrant. Thus, save the coordinates often. A potential advantage of using the quadrants is viewing the same area under different imaging modes.

'X' and 'Y' coordinates can be seen on the [Work] page, 29

Coordinates (NOTICE)

which update in real-time. Coordinates can be “bookmarked” by typing alphanumeric text into the rectangular text box in the ”Stage” section, above the

Saves coordinates include 'X', 'Y', 'T' (tilt of the sample stage) and 'R'. The user is advised to save coordinates often.

'R' (rotation of the stage) menu-box, and press {Enter}. Firstly, focus the image under 'continuous scan'. 30

Single scan (NOTICE)

Access the [Single Scan] feature from the [Scan] menu then choose the resolution. Start with [11.77] from the 'High' column.

The image obtained will bear significantly lesser “noise” and thus may seem less sharp. 'Single scan' images are used as the final images/pictures of the sample and are saved in the TIFF format. Scanning shall stop once a single scan has been executed.

8

[File] menu → [Save] menu → [Image...] to save the

31

Saving the images

image. The images are to be saved in a folder under

The images are saved on the second computer because the

the user's or supervisor's name in the

hard-disk on the main FEI computer is of very limited

location. Press {2} on the 'Raritan Compuswitch' box to switch to computer

capacity. The second computer also has a finite capacity and so the user is requested to transfer the images from this

number 2. The images shall be found in the “UserFiles” computer onto removable media or the internet, if provided. folder in the “Sharefolder” on the desktop. It may be accessed through [E-Beam] menu → [Imaging 32

'UHR' (ultra-high resolution) imaging mode

Mode] menu → [UHR mode]. Minimum magnification for operation of this mode is 1,500 times ('1.5kX'). The user may have to re-adjust the settings of contrast and brightness, focus and astigmatism.

The purpose is to obtain focused images at higher magnifications. At such higher magnifications, 'SRH' mode can be used, though the image(s) may be less sharp (lower resolution).

9

Chapter 4: 'EDX' mode: Determination of elemental composition #

Precaution/Intention

Suggestion/Method

Initiate the 'EDX mode' through the [E-Beam] menu →

[Imaging Mode] menu → [EDX mode]. Set the Commence the 'EDX' mode

accelerating voltage to [20 kV]. If ‘continuous scanning’ stops, resume it. The user may very well have to re-

33

(Energy dispersive X-ray)

adjust the settings of contrast and brightness, focus and astigmatism. 'EDX' mode has a minute window of focus and thus should be adjusted with care.

Additional notes, comments An accurate quantification shall be obtained if the accelerating voltage is set to 20 kV. The “K” ⍺-lines may not be excited if the setting is below 20 kV, and thus the spectrum would be “incomplete”. Due to a significantly lesser sharpness (lower resolution) in the 'EDX' mode, analysis should be started out at relatively low magnifications, if possible.

Simpler method: select [Freeze scanning] from the

[Scan] menu or press {F6}. Other method: execute a 34

Scanning and choosing a particular area

[Single Scan]. Next, select [External Scan] from the

The EDX software, installed on computer 2, is a separate

[Scan] menu. A tick mark should appear next to it. Click software that links with the main FEI xP software. on the [Blank] button in the 'Electron Column' section on the [Startup] page to turn it off (yellow to grey).

35

36

The 'EDX' software:EDAX Genesis

Image of the sample area

Press {2} on the 'Raritan Compuswitch' box to switch to computer number 2. Execute the [EDAX Genesis] software (by its icon on the desktop).

[Image] tab → the large [Collect image] button towards

The selected area of the sample will show up in a corner

the right of the screen.

towards the top-left.

10

From the toolbar above the image, select the [+ +] 37

The scan

symbol (its actual colour is black) to select a point

(1 of 3)

cursor. Click on a point on the image to select it for analysis.

38

The scan (2 of 3)

From toolbar below the image, click the first button from the left,

, it is the 'Start/Stop collection' button (bring

the mouse over it to see the name). ...

One may analyse the elemental composition of a particular point on the sample. The other similar symbols beside it enable an area selection and respective analysis.

An existing spectrum may be removed by pressing the second button from the left,

. Thus the user obtains the

spectrum detailing the elemental composition of the point or area selected. Note that this information needs to be further processed and filtered.

39

The scan (3 of 3)

... The button may have to pressed more than once to commence the 'collection'. If the scan does not terminate in a minute, it may be stopped manually. Click on the last up-down pair of arrowheads

The longer the 'collection' scan runs, the greater the accuracy.

(in the

right-hand side of the screen) to bring up several

40

The elemental composition.

options/features.

The assessment of the elemental composition is not quite

Click the [Peak ID] button (towards the right of the

accurate. The major peaks are normally identified correctly

screen) to have the software assign elements to the

but other smaller ones, including background noise peaks,

peaks, though, not immediately. Otherwise, the user

may be mislabelled.

may have to click the button multiple times for an accurate assessment of elements.

11

Around the [Peak ID] button are two columns containing a list of elements. The left column consists of the likely elements, whilst the right column consists 41

Obtaining useful information: filtering and processing

of a wider range (a catalogue) of elements, most

Some knowledge of the elemental composition of the sample

unlikely. Selecting any element will show, with a thin

is required in order to discern the plausible elements from the

vertical yellow line, its place on the spectrum, and vice

non-existent or unlikely.

versa. An element may removed from the left column and thus from the spectrum by selecting it and pressing the [Delete] button. Pressing the [EPIC] button brings up the periodic table with orbital energy values assigned to each element. 42

Manual detection

Clicking on each element will display the values;

The user may manually filter the plausible elements present.

Clicking on the spectrum will display the constants for

Secondly, the 'Eng' value is of consequence.

that point (in the status bar below the spectrum). If the 'Eng'... 43

...

... values are out of the range of the spectrum then select the [L] option. Click the [Q] button in the same toolbar as the

44

Quantification of the composition

'Start/Stop collection' button to bring up a box

The 'At%' (atomic percentage) and 'Wt%' (weight percentage)

displaying the percentage elemental composition of

values are to be noted.

analysed spot.

12

[File] menu → [Save as] then select the location and type(s) of data to save. Another method is to save screenshots of the display, this may be done by the 45 a

Saving pictures of the spectrum

[Screen capture] function from the [Edit] menu then selecting the sections from the right-hand side and pressing the [Copy] button. The image may then be “pasted” in any application that can handle images such as Microsoft Paint, Word, Powerpoint, etc.

45 b

Saving the spectrum data

Switch to the main [Spectrum] tab. Execute a

The spectrum may be saved in the multi-platform, text-based

‘collection’ scan (the buttons are at the top) and from

'csv' format from the main [Spectrum] tab. The spectrum and

the [File] menu, access the [Save as] function, select

the image of the sample may be saved as images from the

the format, file name and location and [Save].

[Image] tab.

13

Chapter 5: 'FIB' mode: Focused ion beam: milling and etching of patterns or arrays Chapter 5.1: Preparation #

Precaution/Intention

Suggestion/Method

Additional notes, comments

The main purpose of the gallium ion beam is to mill/etch, not image; however, it is, possible to do so but with undesirable 46

Imaging mode

Switch to the default [SRH] mode.

side-effects including sample damage. Milling/etching under the 'UHR' mode at higher magnifications is not an option since this is technical constraint.

Set the magnification to at least '1000X' with the 'FWD' at 5. Since this procedure requires focusing, it is best to centre the cursor on an appropriate point. Select [Zero

Beam Shift] from the [Stage] menu. If the cursor shifts, 'Eucentric height':47

aligning the E-Beam and IBeam. (Step 1)

centre it again on the desired reference point; then, deselect [Update FWD after a Z stage move] from the

[Stage] menu. Set the tilt to 15° by typing “15” (and press {Enter}) in the 'T' box on the [Work] page. The reference point shall then shift. After re-adjusting the brightness, contrast (do not adjust the focus), keep the black button on the stage motion joystick pressed whilst using the joystick to bring the reference point under the cursor. The other way is to adjust the ((Z)) knob on the chamber door. Do not move the joystick laterally.

Setting the eucentric height sets the E-Beam and the I-Beam to focus on the same point. The little black knob on the joystick pad, if pressed, allows for adjustment of the stage height; if not pressed, translational motion would occur. Moving the joystick laterally, when the little black button is pressed, will cause tilting of the sample stage.

14

48

‘Eucentric height' (step 2)

Set the tilt to 30°, 45° then 52° to align the reference

The joystick is not as sensitive and skips often, therefore, be

point with the cursor each time.

patient and careful. An offset of 1 to 2 µm is ideal. If the offset is less than 5 µm,

49

'Eucentric height'... (step 3)

Set the tilt back to 0° and check the offset of the cursor relative to the reference point.

the user may move on, if the offset is between 5 and 10 µm, it is permissible that the user may move on but if the offset is greater than 10 µm then the eucentric height needs to be set again.

50

'Eucentric height' (step 4)

Select [Update FWD after a Z stage move] from the

[Stage] menu then select [Stage is at Eucentric height] from the [Stage] menu. Press the [Source] button in the 'Ion Column' section of

51

Starting up the 'Focused Ion Beam'

the [Startup] page, wait for the 'Ion Emission Current' to fall between 2.1 µA and 2.3 µA inclusive, 2.2 µA being the desired value, then press the [HV] button in the 'High Voltage' section below the 'Ion Column' section.

Eucentric height has been set and registered. 'FWD' will then be registered at 5 mm. If the 'Ion Emission Current', displayed in the 'Status' section near the bottom of the [Startup] page, is below 2.1 µA or beyond 2.3 µA, the supervisor is to be notified. The [Beams On] button activates both, the E-Beam and the IBeam. The I-Beam imaging mode is to be engaged later. The I-Beam column is positioned at an angle of 38°; the E-

52

Tilting the sample

Tilt the sample stage to 52°.

Beam column at an angle of 90°. In order to view the sample from straight up, the stage has to be tilted to 52°, perpendicular to the I-Beam column. The image should have to be focused. The only method

53

Ion beam mode

Shift to an area which the user can afford to have

described thus far has been by way of 'continuous scanning'.

altered; this area may be the edge of the sample or

Gallium ions which comprise the ion beam, however, carry

away from it. The I-Beam may be engaged through the significantly more momentum, and thus continuous scanning

[DB Control] menu by accessing the [Primary Beam - I] in the I-Beam mode causes milling/erosion of the sample in function.

the viewing area. The higher the focus or the larger the 'Ion Column Aperture', the greater the rate of milling/erosion.

15

This is the default setting. It controls the strength of the beam. The higher the aperture setting, the more ions pass through, thus, the wider (since the ions are more spread out) the 54

'Ion Column Aperture'

Start with an aperture setting of [10 pA 30kV] from the

milling.

[I-Beam] menu. Focusing under one aperture setting and milling under another is discouraged as contrast-brightness and focus do not remain constant.

Set the magnification to a higher magnitude (one or two clockwise shifts of the ((Magnification)) dial or more if 55

Focusing

so desired) than the one the user intends to mill at. Engage the continuous scanning and focus the image. Carefully, adjust the stigmator controls.

As previously stated, the higher the magnification when focusing, the more thorough and more accurate the focus. Adjust the stigmator controls regardless, if not to adjust then to at least confirm the lack of astigmatism. Lack of focus and especially presence of astigmatism, will cause the milled patterns to be skewed.

Switch to 'E-Beam' mode from the [DB Control] menu →

[Primary Beam - E], browse over the sample to choose The switch to 'E-Beam' mode is made so as to harmlessly 56

Choice of area

the desired spot for milling; then execute a single 'I-

browse over the sample without suffering passive Ga ion

Beam' scan by the [Grab 1I] function from the [Scan]

milling (of the whole area in view).

menu. This shall execute a quick, single scan of the

The quick 'I-Beam' scan is carried out to obtain the final

area in 'I-Beam' mode whilst in the 'E-Beam' mode then image of the area before the milling. freeze the scanning. Return to the 'I-Beam' mode. Simple shapes to be milled may be selected from the 57

Milling:simple shapes

[Patterning] menu → [Create] sub-menu, and then drawn on the screen. When ready to mill, execute the

[Start Patterning] function from the same menu.

This particular menu contains a few more features and settings that are self-explanatory. If any errors along the lines of “…excessive number of points…” appear, refer to row 61. If the errors persist, draw a smaller pattern or switch to higher magnifications.

16

Stream files (describing a repeating pattern) may be generated by multiple means e.g. stream files may be created indirectly through MATLAB ®. Refer to the webpage:

58

'Stream files' (NOTICE)

http://schottky.phys.sfu.ca/research/splasmons/, more

These are text-based files which are used to create patterns

specifically, the “Stream Files” section, for another

with the FIB e.g. an array of circles or a custom drawing. The

means to generate a stream file and for further vital

file is comprised of information of coordinates, magnitude of

information. Another resource on stream files is

magnification, dwell-time, loop-count and number of points

“Generation of stream files” by Samantha Grist of SFU

(max. 1 million).

ENSC, accessible through Dr. Karen Kavanagh of SFU Physics. Generating stream files (extension: str) from custom images is described in chapter 5.2.

Milling:59

'stream files': (NOTICE: location)

The stream files must be present in drive

(any

location in this drive) of computer 1 for the FEI xP software to load them.

The stream files shall have to be shifted from the . The user is asked to keep the files organised and not leave them in the root directory.

[File] menu → [Open] menu → [Pattern Data] to load the stream file. Select the material file corresponding to the If the exact material file cannot be found, consult the base material of the sample; this may be from the 60

Milling the stream file

supervisor for the closest match.

[Material File] drop-down menu (towards the top-right) on the [Work] page. From the [Patterning] menu,

If any errors along the lines of the pattern/points not fitting in

execute the [Start Patterning] function to commence

the screen appear, refer to row 61.

the milling.

17

Run the 'RunScript' program on computer 1 by the

[RunScript] icon on the desktop. Do not select the loop count option to retain the loop count value specified in

Other options produce no noticeable effect.

the stream file.

When milling commences, a dialogue box shall appear in the

'stream files' and the

Access the [File] menu → [Script 1] to select the script

FEI xP software.

”RunScript” software

file for the program, its name and location is

Once the milling is completed, a few script-related error

Milling:61

. Upon loading notices may pop up, which may be dismissed. the script file, the milling may be commenced by [Run] menu → [Start]. 62

Viewing the result

The user may switch to 'E-Beam' mode, in the same or another quadrant, to view the milled pattern.

Recall, this would be an angled view.

18

Chapter 5.2: Application 1: milling custom patterns #

Precaution/Intention

Suggestion/Method

Additional notes, comments

The pattern must exist as an image in the bitmap format containing a monochrome (black and white) 63

The software: “Patterns”

This software translates the custom pattern/image into

pattern/drawing/image (extension: bmp). When preparing the

a stream file; it may be accessed from the start menu.

image, it is better to remove, if possible, any blank parts of the image. The software does not recognise any other image format.

Select the [MS Windows .BMP] option at the top. Set the magnification in the [Magnification] box; set the milling time in the [Pattern Time, mins] box; select the

[Save Data] option. 64

The procedure

Press the [Calculate] button at the bottom to select and load the bitmap file. Press the button again to bring up the box for the saving of the translated stream file. If a box pertaining to bitmap file(s) comes up, select the

[Cancel] option to bring up the desired stream file box. 65

Visualising a stream file

From the [File] menu, access the [Load .str] function to choose and visualise a stream file.

If unsure of the pattern milling time, set it to 2 minutes. The extension is also to be typed along with the desired name of the stream file. This software can pick up a file from the 'SharedFolder' but remember to save the translated stream file in drive computer 1.

of

19

Chapter 5.3: Application 2: measurement of height, depth or thickness #

Precaution/Intention

Suggestion/Method

Additional notes, comments

The pattern to be drawn is a trench with a sloping base, deepest at the upper face. It is outlined by the main edges of the box. Reduce the size of the box if the software gives an error Access [Patterning] menu → [Create] menu → [Regular

related to an excess number of points; the depth of the milling

Cross Section], then draw out the box such that the top, is of importance here, not the area. 66

Cross-sectioning by slicing

horizontal edge would slice the protrusion in half. If one intends to simply gauge the thickness of the covering

It is assumed that the user has accounted for the

layer then the box may be drawn over a flat section of

preliminaries of angle of tilt, choice of area, focusing, ion

the viewing area. In this case, it's no more than digging column aperture (row 46-57, 61), etc. by ion milling to see how deep it goes. Once the milling is complete, switch to another quadrant (and 'E-Beam' mode) for viewing so as to preserve the box; in case the depth of the trench is insufficient to view the layerbase interface (on the upper, vertical face of the trench), with the user intending to mill again. If the trench does not appear clean enough, especially 67

Cleaning the cross section

the upper face, the 'cleaning cross section' feature may be used. [Patterning] menu → [Create] sub-menu →

[Cleaning Cross Section].

20

Chapter 6: End of session #

Precaution/Intention

Suggestion/Method

Stop the scanning by the {F6} key or [Freeze Scanning] from the [Scan] menu, then set the accelerating voltage 68

Cessation of scanning

of the E-Beam to [5 kV], the [Spotsize] to 3 (if adjusted during the session); set the 'Ion Column Aperture' to

[10pA...]. Turn both beams off by accessing the [Beams Off] 69

Turning the beams off

button in the 'System' section, towards the top-right on the [Startup] page.

70

Vent

71

Sample stage to zero position

Refer to box 2 of row 9 Whilst the chamber is open set the [X], [Y], [Z], [T] (tilt),

[R] (rotation) values to zero. Insert the hex-screw below the sample stage surface

72

Unload the sample

and gently turn anti-clockwise (two or three turns ought to be enough).

73

74

Re-establishing vacuum:

Close the chamber. Access the [Pump] function on the

pumping

[Startup] page.

Log-out

[File] menu → [User Logout] function.

Additional notes, comments

21

BIBLIOGRAPHY •

FEI Company, xP DualBeam Workstation User's Guide, 1999.

•

(Dr. Karen) Kavanagh group, http://schottky.phys.sfu.ca/research/splasmons/, SFU Physics dept.

•

Grist, Samantha, “Generation of stream files”, SFU ENSC dept., 2007.