Science method

FIB - Science method

Explore the latest questions and answers in FIB, and find FIB experts.
Questions related to FIB
  • asked a question related to FIB
Question
1 answer
I am attempting a numerical modeling of a pullout test for reinforced concrete. I have calculated the stiffness parameters following the FIB 2010 standard. I used cohesive contact interaction property for modeling ineraction between embedded length of rebar and concrete. However, for some reason, my bond stress vs. slip curve is not declining as expected. I also tried randomly increasing the stiffness parameters (Knn, Kss, Ktt), but the curve still does not behave as it should. Can you suggest what I should do?"
Relevant answer
Answer
Please check, that you extract data at the right location
Make sure, that the steel does not yield
try to validate your input data - you can use differential equation solver for this => check my matlab files
have a look at the phd thesis of Roman Sedlmair from KIT Germany
  • asked a question related to FIB
Question
4 answers
I am using grids made of Cu for my in-situ heating experiments (from 400°C to 600°C). However, there is a huge Cu- contamination after the heating, which is due to Cu thermal evaporation at high temperatures. Is the any TEM FIB Lift-Out Grids that doesn't produce metal evaporation at high temperatures?
Relevant answer
Answer
Hello Minh-Anh,
FIB lift-out grids made of pure carbon (Carb-N-Grids, offered e.g. by plano-em) can be also used for your purpose.
Best regrads,
Andriy
  • asked a question related to FIB
Question
1 answer
Dear community,
Many papers have been published on FIB/SEM imaging of porous electrodes of Li-ion batteries. A quick Google search only gives the 3D SEM images of separator kindly shared by Prof. Wood from ETH. Seems there is no open source depository of 3D FIB/SEM images of NMC, LFP, LCO, etc.
So, my question is where to find these open source 3D FIB/SEM data (NMC, LFP, LCO)?
My search may be incomplete and any help will be greatly appreciated.
Thanks in advance.
Xiaoguang
Relevant answer
Answer
I found some open-source 3D FIB/SEM data for NMC, LFP, and LCO at various research institutions such as Center for Advanced Life Cycle Engineering - UMD, LSU, and Yale School of Medicine. You can check out their websites to see if they have what you’re looking for.
  • asked a question related to FIB
Question
2 answers
Hello,
Recently, I am learning how to develop a full microstructure-resolved 3D model. And I want to use X-ray nano-tomography or focused ion beam/scanning electron microscope (FIB/SEM) to reconstruct the microstructure of commercial electrodes with sufficient nanoscale details. The microstructure-resolved models can be imported into computational programs to mimic the electrode behavior under the battery operation condition. But I encountered some questions. Firstly, how to add the current collector and separator into the segmented volume to construct a battery half-cell? Secondly, how to export the battery half-cell and import it into computational programs like COMSOL? Does any examples or source code about these questions?
I would appreciate it if you can help me.
Relevant answer
Answer
hello
unfortunately is not mu skill.
  • asked a question related to FIB
Question
2 answers
The excellent book on the Introduction to FIB by Gianuzzi et. al. states the following:
"FIBs are most often used to create features of high aspect ratio (i.e., deep narrow trenches). Sputtered material and backsputtered ions may therefore deposit on surfaces that are in close proximity to the active milling site (e.g., the sidewalls of a deep narrow trench)."
However, backsputtered ions are ions that exit out of the material. I presume these ions exit from the back of the sample. Thus, how could these ions possibly contribute to redeposition of the milled structure?
I tried to visually represent my question with an image, which is attached.
Relevant answer
Answer
Backsputtered does not mean exit from the bottom of the sample. It means they go backwards. Backsputtered ions refer to the sputtering ions that are coming from the incident beam, since you have two systems: the milling beam and the material.
Here you can find slides that will help with visualizing the situation.
  • asked a question related to FIB
Question
1 answer
Hello,
I have a large set of data from a serial imaging FIB/SEM tomography of a superalloy microstructure in binarised form. I was wondering whether there is some sort of programme that allows for automated measurement using the linear intersect method on those binary images. Ideally, I'd be able to compute not only the mean size thickness of the matrix channels, but also get the statistical distribution.
Many thanks in advance!
Relevant answer
Answer
You can use (origin pro) program
Sincerely
  • asked a question related to FIB
Question
9 answers
Hello, everyone
This is biaobiao.
In recent days, I have tried to do EBSD at the FIB milled surface. Well, using a 30 kV Ga+ ion beam, and ion beam currents ranging from 40 pA to 790 pA, I still cannot see the Kikuchi lines.
I also tried to adjust the EBSD capture parameters like exposure time and binning modes low as 1×1, unfortunately, I still cannot see the Kikuchi lines. Of course, no indexing.
The Ga+ influenced depth, in my view, should be around 10-20 nm. Well, the EBSD detects the information of depth as 10 nm, I guess. Is that meaning, I will not get the EBSD after FIB milling?
If anyone has successfully performed FIB-EBSD on Mg, pls. give me your suggestion or experience.
That's it.
Thanks a lot.
Best wishes,
Relevant answer
Answer
Hi Biaobiao! We performed many EBSD mapping on Mg pillars/tensile bars produced by FIB. You have to be extra careful with the preparation and evade any unnecessary FIB scanning on your sample. Use another part for focusing; image only the parts that are essential for positioning your FIB tool. Otherwise the image quality will degrade quite fast. It could also be a redeposited layer that masks your Kikuchi patters. Good luck!
  • asked a question related to FIB
Question
3 answers
To prepare TEM samples from a wire of 1 mm in diameter, I am looking for a suitable preparation method other than the FIB.
Relevant answer
Answer
Thank you so much for the reply.
  • asked a question related to FIB
Question
4 answers
Hi!
I'm looking forward to making a 3D reconstruction of tubular structures in zebrafish using FIB/SEM Microscopy.
I have the possibility of using a Lyra3 TESCAN FIB/SEM for this purpose, but our technicians don't know how to adjust the equipment and prepare our samples for this.
Does anyone have a detailed protocol or a paper that could guide us?
Relevant answer
Answer
Thank you Saad and Manuel. Manuel is correct, CT is definitely a very real possibility (assuming slight to great x-ray density level differences). There would be no loss of material, like can occur with FIB. Plus, CT can be a non-destructive technique. Depending upon the instrument type, CT can have resolution levels of between a few micrometers, to a few nanometers. The latter are usually very limited regarding specimen size. Perhaps x-ray based Micro computed tomography is something worth considering?
  • asked a question related to FIB
Question
6 answers
Recently I have started preparing cross-sectional TEM lamella from the bulk sample using FIB. But I am not aware of how to prepare plane view TEM lamella. Actually, I want to cut a piece of the surface from the bulk sample and wield it to the TEM grid for TEM imaging. Can anyone suggest how can I prepare plane view TEM lamella?
Relevant answer
Answer
I do recommend you read this paper:
Plan-view TEM sample preparation with FIB can take just 2-3 hours with this technique. This is the technique that I have been using that for more than 6 years, and my colleague gave that a nice format in this publication.
  • asked a question related to FIB
Question
4 answers
Hi all,
Are there non-destructive ways to measure the thicknesses of the bilayers made of SiO2 and Si3N4 in a multilayer stack? I have 23 bi-layers, for a total thickness of about 11 um. I was told ellipsometry can't deal with that many layers.
I've tried FIB + TEM (destructive), but it is not a reliable technique nor very practical. Also, measuring the thicknesses of a few micro samples over a surface that is of the order of the cm^2 is not very representative of the entire stack.
Looking forward to hearing your ideas!
Thanks,
Laura
Relevant answer
Answer
I understand you look for a fast technique, but TEM is the best (and surprise that you say it is not reliable!).
Anyways, I can give you a general comment in this case, I suggest you try X-ray reflectivity XRR measurements, if you access to XRD equipment. This is a popular common technique used for determining thickness of many thin films, in particular, very thin layers.
The measurement is definitely non-destructive and quick, but you may need spend some time to fitting the results to get the thickness. To have the easiest and quickest way,
1. grow one layer of SiO2 and one layer of Si3N4 (two different samples + preferably thin layers).
2. do XRR to get thickness of each later.
3. then you will have deposition rate for each layer (already know deposition time for each and now you have thickness from XRR; so, deposition rate is film thickness/deposition time), with a high accuracy not like SEM which has high error bars.
4. finally, grow the multilayers with a high, accurate control over each bilayer thickness.
  • asked a question related to FIB
Question
4 answers
I would like to deposit a single Pt nano-column with GIS and FIB of a diameter <100 nm and height >500 nm. Is it possible? What values of parameters of ion beam (accelerating voltage, current) and scanning (mode, dose, dose factor, pixel spacing, numer of cycles) should be used?
I achieved 200 nm column with parameters as shown in the attachment. I have been trying to fine-tune the parameters but I could not decrease the diameter.
I tried both single point and small square (nominal dimensions 100 nm x 100 nm) as a layout.
Relevant answer
Answer
Hi Piotr Jenczyk I guess for these experiments you use some bulk substrate (e.g. piece of silicon). Instead, use membrane (e.g. TEM membrane on a grid) as substrate for deposition. This will significantly reduce the parasitic radial growth, which is contributing the diameter of your nanowires. So that in the end you will have a small diameter nanowire standing on a mebrane instead of bulk sample. Then, it depends on the purpose you intend to use this nanowire for. This trick is clearly possible only if bulk substrate is not necessary for your demanded application.
  • asked a question related to FIB
Question
7 answers
Hello all
I have to get an SEM image for my perovskite LED device cross section but I am not able to get a clear image. It is very blurry and I am not able to get any information from there. The machine I am using is Tescan FIB FERA. Can anyone help me with this?
Relevant answer
Answer
You need to look for a microscope JEOL
  • asked a question related to FIB
Question
7 answers
Hi Fellows, I would like to know if there is a good way to characterize surface defects or strain. Our recent finding shows that scratched surfaces show different electrochemical properties from non-scratched surfaces. However, the scratch did not generate any SEM-level cracks/fractures (invisible in SEM). I am thinking either nano-cracks were generated on the surface or a strain field was built up. My initial thought was using TEM to look at it. However, the sample preparation may cause new strain field if a FIB method was used. Is there any way to detect such small defects (if any) or the strain field?
Relevant answer
Answer
If surface scratches are within nanometer scale, you may use AFM instead of SEM or TEM.
AFM deals with surface topology, and data output are Roughness Parameters, where you can relate them with the change of electrochemical properties.
  • asked a question related to FIB
Question
5 answers
I am doing some FIB cuts and analyzing my layer stack. I always see dots in the InP and InGaAsP layers, but I don't know their origin. These dots do not appear when I do a SEM of a cleaved sample, so I assume the origin is related with the Ion beam process. I attached a picture of a SEM image after an FIB to make clear which dots I am referring to. Any help or reference to solve this question is highly appreciated!
Relevant answer
Answer
I am looking to synthesize InP or InGaAsP colloidal solution, Could you help me?
Thanks.....
  • asked a question related to FIB
Question
2 answers
I want to see the cross section of PDMS substrate.
As far as I search, direct focused ion beam irrdiation makes the PDMS surface wrinkled.
Before FIB milling, if the metallic coating (Pt, Os, etc) with O(1nm) is performed, is it possible to do FIB milling of PDMS layer as minimizing the wrinkling?
Thanks in advance.
Relevant answer
Answer
You could also consider cooling the sample with either thermoelectric or cryogenic stage to avoid artifacts from localized heating by ions.
  • asked a question related to FIB
Question
5 answers
I have attached a metallic thin sample in Si substrate using FIB. After that, I have made the connection by depositing platinum in FIB with the sample and the pre-pattern platinum electrode. The prepattern platinum electrode is made by photolithography which has contact resistance around 10 ohms. But after making the connection with the pre-pattern platinum electrode by depositing the platinum in FIB the resistance become very high.
Can anyone suggest how can I improve my connection?
Relevant answer
Answer
Typical FIB-deposited "Platinum" is in reality a composite of Pt particles with dimensions on the scale of ~5nm - ~8nm suspended in the matrix of amorphous carbon with some Ga contamination. Exact composition is heavily depent on the deposition conditions (precursor gas flux and beam parameters) but you can expect that less then 50% of the deposited material is actual Pt, while rest being mostly C and Ga in single percentage. FIB Pt deposits have very high resistance.
To get low-resistance contacts you can try:
1. FIB deposition of Cu from Cu(hfac)2 precursor. Good luck getting hands on only 5 or 6 FIB instruments with such capability that were ever made and sold commercially, but if you are lucky to find one of them then purely metallic depo is straight-forward.
2. FIB deposition of W from W(CO)6 or Mo from Mo(CO)6 precursors. These are commercially available, and Mo precursor can be charged into any system designed for W deposition. Resistivity is still fairly high, but you can expect metal content ~>60% and with properly designed deposition recipe resistivity 1/2 to 1/3 of Pt deposits.
3. You didn't mention lateral dimensions of your sample, but on the scale of >~20um you can try using micro-manipulator to position droplets of Ga to wet your contacts and establish low-resistance contact.
4. Increase area and thickness of FIB deposition to lower contact and bulk resistance.
5. For W and Mo FIB deposits - create a recipe working in near-sputtering deposition regime, to increase Ga content in the deposited material. Not sure if this approach would work for Pt - haven't tried.
6. If the dimensional scale of your sample is large enough, then use laser-induced Pt deposition. It is commercially available now from Varioscale Inc., or you may be able to find one of the older systems from former Revise Inc.
7. Do a hybrid lift-off: dispense thin layer of photoresist on your sample with ultrasonic nozzle, selectively expose areas of contacts with laser ablator at low power or with just OM light by reducing illuminated area with field aperture, use ordinary sputter coater to deposit metal, and finally dissolve resist in solvent.
8...Multiple other approaches are possible, depending on material and dimensions of your sample, purpose of the whole exercise, availability of equipment, chemicals, funding, etc....
Good luck :)
Valery
  • asked a question related to FIB
Question
5 answers
My point is - I want to get a 3D model of a sample with nano-scale resolution but with a relatively large field of view (tens of microns). I'm planning to use FIB for 3D reconstruction. Have you seen any study about the large field of view FIB imaging? I'm particularly interested in the application of FIB for geology. Thank you in advance for your help
Relevant answer
Answer
From my personal experience - 60x40x25 um with 10 nm voxel size (resin embedded biological sample). But don't forget about drift/shift during the data collection, it decreases the final (after slices registration) volume. I strictly recommend Dragonfly software for rendering and segmentation.
Good luck!
  • asked a question related to FIB
Question
9 answers
I need to find a method to cut (i.e. remove) the unwanted parts of my polymeric sample under a microscope. The sample is small and I need to have cutting-accuracy about 1 micron.
Now, I am planning to use FIB for this purpose. However, FIB's resolution is much more than my needs.
Do you know an alternative method for me?
Relevant answer
Answer
It can be trimmed using an ultramicrotome (normally used for TEM slices preparation) with a glass or special 90 degree diamond (if high precision required) https://www.diatome.ch/en/products/ultratrim.asp
Good luck!
  • asked a question related to FIB
Question
13 answers
Dear colleagues,
A good FIB-SEM data stack can contain a few thousands pictures. It is very tricky and annoying process to segment them all manually. Which software do you use (real practical experience with big data) for such tasks?
Cheers,
Denis
Relevant answer
Answer
You can also try Dragonfly (https://www.theobjects.com/dragonfly/index.html) from Object Research Systems, it is free for non commercial use.
Dragonfly has many segmentation tools from active shape to deep neural networks. The following video, (https://www.youtube.com/watch?v=1WVlskyuw94) is a deep learning tutorial.
Do not hesitate to contact me if you want more information.
  • asked a question related to FIB
Question
6 answers
Dear 'Named Data Networking' researchers,
As you know the current Vanilla NDN works over IP. If we assume that NDN architecture become the used Internet Architecture instead of TCP/IP, what will be the address of the final users (source of interest packet)? The physical address?!
In other words, does the interface in the FIB equal to physical address?
If not, for the case of wireless interfaces, we may have multiple users connecting through the same interface entry (university router for instance) How the address problem is solved when the data arrives back?
Relevant answer
Answer
In a non-local network context, each FIB entry contains a name prefix and a network interface (which represents a next hop). When running over IP, the network interface could be represented as an IP tunnel to the next hop.
In a local network, if NDN is running directly over link protocol (like Ethernet), then yes, the local FIB entry may contain a link protocol MAC addr.
Specifically, for wireless local network, researchers from Stony Brook University found there is no need for a per-host addr, so they are developing a name-based link layer protocol which focus on the data name instead of a per-host MAC addr.
  • asked a question related to FIB
Question
4 answers
Our FIB source was opened to air prematurely resulting in gallium oxide (water insoluble) coating some parts of the ion source. Does anyone know a simple means of removing it ? I guess HCL is best but just thought it'd be worth asking anyway.
Relevant answer
Answer
Hello Jamie,
we use phosphoric acid to thin our Ga2O3-samples. For your orientation:
Samples in (100) orientation have an etch rate of nearly 17 nm/min, if we use H3PO4 - 85% at 140°C.
I don't know, what it makes with stainless steel, but I think, HCl is more aggressive than phosphoric acid.
Best Regards
R. Mitdank
  • asked a question related to FIB
Question
19 answers
I am analysing wear track of CoCrMo alloy using FIB-SEM. Unfortunately, every time Beam is shifting out of sight after some time. I am mounting my sample using carbon tape and later painting the side of the sample using Ag paint (from sample to sample holder). If anyone has faced a similar problem and found a solution please share if you can.
Thanks in advance!
Relevant answer
Answer
It's probably due to stage drift as it sounds like your sample should be well grounded. If as Denis has implied you are doing a 3D volume slice and view, then I suspect that you are not letting the stage stabilize before beginning. Once you have the stage in final position wait about 1 hour before beginning. How long depends on the quality of the stage you have.
If this is not the case then I need a bit more info from you about what you are doing.
  • asked a question related to FIB
Question
8 answers
I'm modelling a RC beam structure using LSDYNA. I want to include the rebar bond-slip relation in the model. The *CONTACT_1D has different parameters, such as Bond Shear Modulus GB, Maximum shear strain displacement SMAX, and Exponent in Damage Curve EXP.
- Are there any recommended values backed up from your experience ? Any guidance through the calculation of those parameters ? I read few literature and they refer to FIB Model Code for Concrete 2010, clause 6.1.1 and Table 6.1-1. But no any clue regarding relating those to GB, SMAX, or EXP. And also, what are the units for each? Is it MPa or MPa/mm for GB ? mm or unitless for SMAX ? Because I came across both units in some literature.
- Is it a must to have mesh conformity between rebar and concrete to implement a correct *Contact_1D ?
Relevant answer
Answer
Thanks for your cooperation, will email you soon.
Regarding your inquiries:
1- You can find the bond stress value from the FIB Model Concrete Code 2010, table 6.1 for ribbed deformed bars (according to the interface bonding condition). From the same table you can find Smax. For GB, You may then simply use the formula Smax=Bond Stress/GB. Note that it's unit sensitive. EXP is case dependent, no recommended values given the fact that it's often used to fit your curve based on trial approach.
2-For the rebar coupling in concrete, you may use *CLIS. Recent versions of LSDYNA solvers recognize *CBIS (shown slightly better results). So far, I haven't dealt with ACNC or BIS. If you're interested in rebar coupling, you may check Len Schwer's article entitled "Modelling Rebar: The forgotten sister in RC" (https://www.dynalook.com/13th-international-ls-dyna-conference/constitutive-modeling/modeling-rebar-the-forgotten-sister-in-reinforced-concrete-modeling). Will publish one article soon addressing same topic with focus on prestressed tendons coupling, if you're interested may notify you once it's available.
Cheers!
  • asked a question related to FIB
Question
4 answers
Im trying to find out if it would be possible to create a stencil from a metal plate by removing a thin strip of material all the way through. The groove would need dimensions of : 100nm wide and about 500 micrometres deep. The length doesn't really matter. Im trying to think of ways to grow nanowires using a metal stencil instead of growing onto a layer of resist and removing via liftoff. Iv heard that FIB can reach the resolution I need but not sure if it could reach the depths im looking for.
Any suggestions? Thankyou
Relevant answer
Answer
I second Dimitar's answer And add that you more than likely will need a femtosecond laser specifically. With longer pulse width, especially close to nanosecond, you might end up having melt zones near your machined edges. These melt edges may be in the form of microscopic bumps. I would try to avoid such artifacts for a nanostencil application.
  • asked a question related to FIB
Question
9 answers
I covered (MBE) the half of my nanowires (1um long and 50nm diameter) with a 20nm layer of Fe. Now the question is, how can I destroy the Fe film to release the nanowires and disperse them in solution without destroying them? Cutting the nanowires one by one with the FIB is not really working well.
SEM images are attached (the maximum that I was able to break the Fe film).
Thank you very much for the answers in advance. I hope someone has some ideas :)
Relevant answer
Answer
Its a good news:)
Frohe Weihnachten und ein glückliches Neues Jahr!
  • asked a question related to FIB
Question
6 answers
I am using molecular dynamics to study Ga interaction with Silicon. The simulations at low kV (1-5kV) with 0.1fs time-step works well and are in accordance with SRIM generated values. The simulations at 30kV, however, with time-step 0.1-0.002fs do not predict actual results (the Ga ions just passes through Si lattice and travel more than 100nm Si depth), potentially arising from interaction issues. I am using a combination of ZBL and tersoff potentials. Has anyone encountered such issue in their MD simulations? Any feedback or suggestion in this regard would be highly appreciated.
Regards,
Vivek
Relevant answer
Answer
Dear Vivek,
it might also be useful to you to have a look at Julien Guénolé 's latest work on this type of problems.
Regards,
Enrico
  • asked a question related to FIB
Question
7 answers
I am looking for performing some EBSD analysis on electroplated Indium, The tough task is preparing it, its very soft and ductile metal. Gallium beam from FIB is melting Indium and even electron beam assisted platinum deposition is deforming it. Similar result with Argon ion beam too. Is there any mechanical precise way such as vibromet or power head assisted polishing can help in this situation ? Aslo how much effect does surface roughness have on indexing the patterns? Because the specific chemistry I am using to plate Indium has pyramid type of micro structure with sharp apex on top, is there any way I can polish few nano meters away and look for pattern from surface rather than cross sectioning?
Relevant answer
Answer
Well, although Hikari Pro is possibly not the best detector for this application, the EDAX system is a suitable tool which should be able to solve this problem. Topography is certainly annoying but actually only causes shadowing so that a) you cannot image the entire surface and b) you will have only partial patterns sometimes. The first you cannot prevent, and the second should be partially compensated by the application of dynamic background processing, even in OIM. The result will be a map with a higher amount of non-solved solutions but it should not be zero. If this happens, something is wrong in your measurement setup. On the other hand, without seeing the samples I cannot give you a real advice. Could you post some typical patterns or acquired maps?
To overcome this problem at least partially, you could tilt your sample to lower angles in order to reduce the shadowing caused by topography. To this aim you need to use a higher working distance, otherwise you are running into the next trap: the surface will become visible at your screen. I did this for testing how far you can go and the limit I reached in those days was about 50-55°. It depends on the SEM adaptation of the detector, and its flexibility (Bruker always and Oxford recently offer a tiltable detector which is perfect for such applications). Moreover, you could pull out your detector by some millimeters which gives you some additional degrees. Nevertheless, all these options are connected with an increase of necessary collection time. On the other hand, 20 years ago we all did measurements with 10 patterns per second and less.
If you need information about the texture, why you do not use XRD? It is anyway a more reliable technique for statistical reasons. If you do EBSD you always have to ask yourself whether you can "trust" the map size regarding the displayed quality. You generate nice (beautiful) maps but it is hard to say how much it really tells you. Unfortunately, there is no big progress concerning a useful interpretation of data. All systems impress prospect users by most fast OR (rarely AND!) most beautiful maps. I havn't seen many applications which impressed the community by an unbeatable interpretation and solution of a real materials problem. The generation of beautiful maps with nearly no (displayed) zero solutions are no real problem to me.
  • asked a question related to FIB
Question
4 answers
I need to solve the ion mirror phenomenon that occurs in FIB
Relevant answer
Answer
There are indeed some other effects which might have impact like at high magnification the reduction of resolution. In case of a wider beam theoretically also the contrast might be influenced since the probe size changes. Even the very simple influence "focusing" at different beam currents might be one factor. Moreover, if I take my common image optimization into account...I do not know actually which gain (contrast) I used for the imaging after optimization. In other words, how do you know that the contrast improves? Do you really "save" the electron signal as numbers, or only the image itself? If there is less noise the contrast simply seems to be improved, but actually it isn't. You also should answer my first question :-) . WHICH contrast? About which images you are talking? SE (which one), BSE (Which one)? At which acceleration voltages you are talking? I assumed common conditions like 20keV, 1nA...
However, in order to prevent any speculations you should post both images with all available parameters selected during imaging.
  • asked a question related to FIB
Question
5 answers
Like FIB-TEM.
I am looking for a technique by which polymer composite properties remain constant.
Plz insight us
Thanks in advance.
Relevant answer
Answer
Dear Bhaskar;
You have three choices:
1. You can prepare a very thin composite to see sharp nanofibers in the FE-SEM images (This method is specially useful for hydrogels reinforced with nanofibers).
2. You can provide a cross section and see the dispersion of fillers in the coating matrix ( ).
3. You can used AFM analysis (topographic and phase contrast images) to investigate the nanofillers.
Good luck
  • asked a question related to FIB
Question
4 answers
Actually, i am looking forward to prepare lamella with thickness about 50 nm from silicon nano wires on silicon wafer substrate, using it to study its interface with cells, but i don't know the exact procedure of doing that. I have a FIB-SEM and TEM.
Relevant answer
Answer
Dear Ashraf many thanks for your detailed answer. I would like to ask you if you can kindly send to me the detailed procedure if it is possible? i will be thankful.
  • asked a question related to FIB
Question
4 answers
Focused ion beam (FIB) devices can generate beams with a diameter (FWHM) of less than 10 nm. What are the methods for measuring diameter of Focused ion beam (FIB)?
Thanks
Mohsen
Relevant answer
Answer
There are several technique that can be used to measure the FIB beam size. It used to be a top topic in literature. See these articles:
  • asked a question related to FIB
Question
4 answers
Recently I am using Focus ion beam to prepare TEM lamella, but came to a dilemma that the crystalline sample is either too thin for SAD (losing Kikuchi lines for two beam conditions) or too thick for HRTEM. The interested area is very localized. Could some scientists or experts give me some clues on the critical thickness for both that? (80-120 nm)? Thanks a lot in advance.
Best regards,
Sincerely,
Relevant answer
Answer
Dear Cao,
generally, the lamella should be as thin as possible :-) But of course there are some trade-offs involving sample preparation technique (if you preparing lamellas in a "flag" or "frontal" way), that you have to take into account to avoid either bending, redeposition, Cu contamination etc. Another factor is a TEM that you are using (for instance 200 kV vs 300 kV), and of course the type of the sample you are preparing (ceramics, metals, ...). In my experience 100 nm metal lamellas are already good for STEM, while way too thick for HR-TEM, therefore if possible I'm trying to use another preparation technique for such analyses.
Another rule of the thumb that can be useful: if it is possible to observe Kikuchi bands, sample is usually too thick for HR-TEM. And since lamella (should have) uniform thickness, it will be challenging to satisfy both conditions. If I understand correctly, you are interested in SAED, so probably just using Kikuchi bands for finding the proper zone axis, right? Try to find some other way to properly align your sample (maybe in thicker way of lamella, where it is attached to the support?), and go for the thin as possible. Also SAED of very thin samples has it's own benefits!
Good luck!
  • asked a question related to FIB
Question
6 answers
I am working on soft lithography and trying to modify the patterned silicon wafer (pattern made by FIB) surface with trichloro(1h 1h 2h 2h-perfluorooctyl)silane, according to this instruction: https://hms.harvard.edu/sites/default/files/assets/Sites/Microfluidics/files/Silanization%20of%20Photoresist%20Master%20Protocol.pdf
But I found that the silane chemical is unevenly distributed on my wafer and dirty, even damaged my pattern on Si wafer, does anyone know how exactly I should do the modification?
Relevant answer
Answer
the smallest size is 250 nm, and actually there's no photoresist, the features are made from focused ion beam.
  • asked a question related to FIB
Question
11 answers
I have some cold-rolled NiTi sheets (0.8 mm in thick). I want to observe the microstructure of the side face using TEM. So how to prepare a TEM film in this case. FIB is costly. I just want to use mannual grinding and then twin-jet electropolishing.
Relevant answer
Answer
Hi Li, I'm attaching a low-mag image of NiTi sample, which was first dimpled, then electropolished and finally ion-milled to remove the oxide layer. The last step produced a lot of "curling", but anyway the foil was extremely thin over very large area. I think that was bacause of the pre-thinning (dimpling).
  • asked a question related to FIB
Question
5 answers
I am currently working on new TBC materials which can replace the famous 8 wt% Yttria stabilized Zirconia. I would like to know If FIB SEM can be used in analysis of such materials?
Relevant answer
Answer
What puzzle me is: Do you have a real question, or do you really simply want to know how you could use this very expensive toy (FIB) for any type of characterisation, possible a material like TBC? Why don't you simply mount it in the FIB and look what happens?
Until now I understood Researchgate as opportunity to find answers on questions, and not to find even the question of a not yet existing problem.
  • asked a question related to FIB
Question
5 answers
I am planning to deposit a thin gold film on YIG and after some patterning using FIB, i need to remove it using an etchant. I need to make sure if the chemicals in the gold etchant wont etch through YIG or not. 
Relevant answer
Answer
Most common Gold Etchant we use is a solution of I2, KI and Water, it's commercially available as TFA from Transene. But I have no idea if it etches YIG. Also just started to use another cyanide based solution called TFAC that one has Zn and KCN plus some KOH. It's called TFAC from the same company. Finally , I've also removed Au by ionmilling, which could work depending on aspect ratio of your pattern and etch rate of YIG (which I have no idea about)
  • asked a question related to FIB
Question
4 answers
I am planning to make patterns on YIG thin film using Focussed Ion beam. But YIG thin film is insulating and deviates the ion beam. I am planning to deposit a thin film of metal, such as gold and then perform patterning using FIB. I would etch the gold layer using an etchant but would it also etch through YIG? 
Relevant answer
Answer
Sorry, but I have no idea why the colour of the TF would affect the conductivity of your sample. On the other hand, if there are impuritis present, that are causing the coloration, then this may be the case.
I think it is rather easy to measure conductivity and compare it to the reference data. Multimeters are usually found in every laboratory, or you can ask the technician or even the repairman...
  • asked a question related to FIB
Question
3 answers
I want to use FIB milling technology for drug localization. Could any one suggest me to some articles regarding this topic.
Relevant answer
Answer
Do you mean drug localization within biological tissues?
  • asked a question related to FIB
Question
3 answers
I have a 50nm Yittrium iron garnet which is highly insulating and gets charged up while trying to create patterns using Focused Ion beam. I need to create patterned structures on the thin filmusing FIB.  Is it possible to coat the thin film with some kind of metal which will get rid of the charging problem? And then etch out the metal coating. If so, what metal should i use and which etchant that wont affect the underlying YIG film. 
Relevant answer
Answer
Dear Ashish,
I have no experience with FIB on garnets. In the past however, we have done patterns with my colleagues, on yttrium garnet films on GGG, by a chemical method. You will find details in the paper (available on research gate):
“Ferromagnetic films with magnons bandgap périodic structures: magnons crystal”
YU. V. GULYAEV, S.A. NIKITOV, L.V. ZHIVOTSKII, A.A. KLIMOV, Ph. TAILHADES, L. PRESMANES, C. BONNINGUE, C.S. TSAI, S.L. VYSOTSKII, Yu. A. FILIMONOV
JETP Letters 2003, 77, 10, 567-570
Best regards.
Philippe.
  • asked a question related to FIB
Question
3 answers
I am investigating some off-stoichiometric delafossite structure by TEM. I am observing some missing atomic lines (10- 20 atoms missing). This happens for many grains (hence not an isolated case) but not for all samples. Therefore I would like to know if this defect is characteristic for the sample or is possible to appears during sample preparation. During this preparation process I am using a FIB based on Galium. My question is then: does somebody already observed this kind of defect appearing during an ion bombarding? 
Relevant answer
Answer
Thank you for answers. The missing atoms are copper. By XPS we determined a huge Cu deficiency but we didnt expect such arrangement, There are all over the sample and at random orientation sut we might exclude influence of ion beam dirrection, However we obtained this only for samples deposited in specific conditions (but not for the others) and these defects are dissapearing after an annealing. I would like to know how they are dissapearing as the weird stoichiometry remains. 
  • asked a question related to FIB
Question
2 answers
Please write which kind of project you started. I am interested in FIB analyze after fs laser irradiation of thin films.
We have had in 2011 a common in SCT a paper titled: Femtosecond laser modification of multilayered TiAlN/TiN coating.
I wish you success, Biljana  
Relevant answer
Answer
Dear Biljana,
In the meanwhile I become FIB-SEM expert and started High Resolution FIB Tomography on material science field. In the project automated serial sectioning with advanced drift correction, real time slice thickness determination, auto focusing and auto astigmatism was developed from instrumentation part. The automated algorithm is basically self learning regarding drift compensation and allows acquisition of narrow and reproducible slices with thickness down to 5 nm (voxel size of only 5nm!) on complex porous metal-ceramic composites (it is even easier on metals). Within the project advanced image processing and fully automated 3D watershed segmentation algorithm as well as complete 3D quantification were developed on several materials for energy harvesting, energy conversion and energy storage. In short words, the developed 3D analytical method allows comprehensive 3D quantitative material characterization.
At the same time new detection technology was integrated into 3D imaging, like low voltage HR-SEM with energy filtering of back scattering electrons and/or use of pre-monocromated electron beam to achieve true surface imaging at low and very low voltages to avoid "beam damage". With this kind of imaging it is possible to detect nano-compositional differences based on phase contrast - those are basically analytical images which can be normally used as 2D information or further extended into 3D.
FIB-SEM, together with knowledge and experiences, is very powerful tool regarding material characterization. For sure it can be used to extend further your characterization of laser treated samples. At the final point is also possible to cut out thin lamella from chosen surface area, using FIB, and transfer it into atomic resolution scnning transmission electron microscope and extend research down to atomic level.
For additional info I am available on email: gregor.kapun@ki.si
With kind regards, Gregor
  • asked a question related to FIB
Question
6 answers
Focused ion beam (FIB) instruments can provide beams with a diameter (FWHM) of less than 10nm, however, the interaction between ions and target occurs over a large volume, given by the influence of the probe tails and multiple scattering laterally and the depth penetration of the ions in the vertical direction. What are the smallest nano-structures that have been made by FIB?
Relevant answer
Answer
You can learn about feature size and precision techniques in this paper.
  • asked a question related to FIB
Question
2 answers
The straightforward way of converting probe current into ions per second (A-->C/s-->ion/s) and dividing by the beam area is giving me values much higher than usually quoted in literature.
Am I forgetting to consider some aspect of the rastering? I couldn't find any source describing this, among lots of papers and books about FIB.
Thanks in advance,
Relevant answer
Answer
ok I found where the confusion lied, it was on the typical exposure times that were much smaller than what I initially thought.
  • asked a question related to FIB
Question
6 answers
I am trying to test a custom implementation of a packet forwarding algorithm for an IPV4 router. To test the performance of my algorithm, I need the forwarding table (FIB) from a real router and a trace of the packets received by the router. I was looking at www.ripe.net and www.caida.org, but could not quite understand how to get the exact information I need. Any help from the community would be highly appreciated.
Relevant answer
Answer
The FIB simply creates a mapping of IP addresses to MAC address in TCAM which results in a hardware lookup for packet forwarding decision against all mappings in the FIB in one parallel iteration. Therefore, to a large extend the FIB is static and as such is only adjusted with changes in the RIB which fundamentally is used to determine packet forwarding (through routing protocol updates and convergence), which is forward to and stored in FIB (e.g., a TCAM table) for the actual forwarding. To that end, if you are using a custom packet forwarding algorithm what is more efficient and faster than the TCAM, wouldn't you be more interested in the RIB data that installs IP-to-MAC mappings in the FIB? Can you supply more information about what exactly you are trying to measure in respect to the packet forwarding please.
  • asked a question related to FIB
Question
7 answers
I am working on characterizations of mullite needles, which exhibits nano-scale size, in order to investigate their Al/Si ratio. The needles possess 100-200 nm long and about 20-50 nm diameter in average. And the needles are embedded in a silicate-glass matrix. 
I have done SEM-EDS but I could not get the Al/Si ratio since the EDS signal were not indicated mullite characteristic. It supposed to have large interaction volume and the obtained signal included both mullite and glass matrix. I also performed FIB/SIMS which is about 10 nm of interaction volume, again I could not get the signal.
I am thinking what can I characterize the needles chemically to find out the Al/Si ratio.
Any suggestions will be really appreciated
Relevant answer
Answer
Dear Alexander Prof Jose and Tahani
I really appreciated your suggestions, I will try to use the STEM.
Dear Kun
You are so right, actually I did etched the sample using HF but the result was what I mentioned. Unfortunately, the sample also contains some amounts of quartz; therefore, neither XRD nor XRF can differentiate the Si in mullite/ and quartz forms.
Dear Vijay
Thanks for your advice but I have no idea about the  Pair Distribution Function, I may spend more time to read it.
Any more suggestions are very welcome.
  • asked a question related to FIB
Question
1 answer
Normally we believe Xe ions must be more detrimental to the specimen's surface compare to Ga ions, since they are heavier and larger.
So personally I would not consider PFIB method suitable for TEM lamella preparation.
But I heard somewhere that using PFIB (using Xe) the amorphous layer of the TEM lamella is even thinner compare to the normal FIB (using Ga)! Physically I can not digest this as a fact!
Any experience?
Relevant answer
Answer
The range for Xe is lower due to increased stopping power so the amorphous layer will be thinner. The sputtering rate will be higher, so this may seem counterintuitive. Download SRIM and see for yourself! http://www.srim.org
  • asked a question related to FIB
Question
10 answers
I am planning to use the diamond themselves as sample container (to avoid flaws related to noble metal use) for a Hydrothermal Diamond Anvil Cell.
To do so, I need to have a square 300x300 microns and 50 microns deep recess milled on the culet of one of the anvils. FIB is the only technique which can produce a virtually perfect shape, which is paramount for my experiments (I tried laser milling but it does not work). I also need to FIB-cut glass wafers 200x200x40 microns dimensions out of glass chips (roughly 1x1x1 mm size, but could be made bigger, if necessary).
Relevant answer
Answer
we routinely machine structures of these dimensions in diamond using laser micromachining - we have vast experience with working with diamond! Are you still interested to do this or did you solve the problem
  • asked a question related to FIB
Question
3 answers
Dear All,
I am working on using the FIB to create 200nm-in-diameter cavities. But I would love to have more control on the geometry of the FIB. So I am wondering what would be the controllable variables in the FIB processing. Any opinion is welcomed!
i.e current, loops, dwell time, etc. 
Letian
Relevant answer
Answer
You may want to play around with the defocus of the FIB when milling. That will alter the beam profile and effect your cavities. 
  • asked a question related to FIB
Question
3 answers
Sample Preparation, HR-TEM, Ion Milling, FIB, Glaze
Relevant answer
Answer
I would try it with normal cross section preparation; see the basics in our old paper:
  • asked a question related to FIB
Question
10 answers
Our group is working  with coatings and we have done few erosion tests. We need somebody, who can help us to do FIB sample preparation for our coatings. We are planning also to do some corrosion tests and wirite few publikations. Sharing authorship will be a possible.
Those interested, please send message to my RGate mailbox or here.
Thank you
Relevant answer
Answer
Hello,
We have a strong experience in the area of focused ion beams and TEM sample preparation. Southern Federal University (Taganrog-Rostov, Russia).
Kind regards,
Alexey.
  • asked a question related to FIB
Question
11 answers
Assume you have two FIB system with almost the same specifications, and the only difference is that one of them can provide a probe current of up to 60 nA and the other one up to 100 nA.
But the first one has other advantages over the second system.
So, I want to know how important the FIB probe current is (for 3D EBSD and EDS analysis). Is there a significant difference between 60nA and 100nA, when it comes to milling speed and resolution?
Relevant answer
Answer
If your main application is going to be FIB tomography for large areas, you don't only want to consider the maximum beam current, but the beam current density. This can vary significantly depending on the quality of the FIB optics. So, just because one manufacturer claims to be able to provide higher current, if that beam has huge beam tails it will be of limited practical utility for 3D reconstruction applications. You can estimate this by simply putting the beam into spot mode for a controlled time on a sample (gold film on Si will provide good contrast) and measure the beam spread.
  • asked a question related to FIB
Question
4 answers
How is the energy of the FIB dependent on the process parameters.? In other words what is the relation (mathematical) between beam voltage, beam current, dwell time, etc on the energy of the ion beam?
Relevant answer
Answer
The number of atoms sputtered by the incident Ga+ beam which is known as the sputtering yield Y(Eo) is proportional to:
Y(Eo) ~ NS(E)∆xo)/ Eo
where Eo is an arbitrary minimum energy of the ion beam based on the surface binding energy of the material, N is the number density of atoms, S is the stopping power (dE/dx) and xo is the depth interval for which the atoms ejected have energy >Eo. This is from Gianuzzi and Stevie 2005 (Book link attached).
Regarding beam energy, Most FIBs have fixed energies from ~5kV to 30 kV in multiples of 5kV. It depends what you are trying to do with the FIB beam. I use an FEI Quanta 3D for TEM sample preparation and we typically use a 30 KV beam.
  • asked a question related to FIB
Question
5 answers
I would be most interested in an application capable of running machine learning algorithms
Relevant answer
Answer
Sorry plz read ImnageJ as ImageJ, it was a typo!
  • asked a question related to FIB
Question
3 answers
I have seen some systems, such as FEI requires a particular sample preparation (rectangular thin samples with 90 degree edges). Their configurations can only do 3D EBSD on the edge of the rectangular specimens.
It means that we can not do 3D EBSD on the normal 2D EBSD samples (normal mounted samples).
Is this the normal procedure for all the 3D EBSD configurations our in the market? Is there any possibility to run 3D EBSD tests on the normal samples, i.e. not those special rectangular shapes?
Any specific guideline for sample preparation for 3D EBSD analysis, using normal grinding/polishing equipment?
Relevant answer
Answer
Please see the attachment. it was carried out by Raabe and Zaefferer. You can find important information.
  • asked a question related to FIB
Question
13 answers
For my experience, every time I prepare a TEM lamella from a bulk Al sample it starts bending when its thickness is below 100 nm.
It cannot be charging because there is electrical continuity through the Pt and the Omniprobe needle.
One reasonable explanation would be partial melting, but is that possible when using as little as 0.28 pA and 16 kV? Al has a melting point around 930 ºK..
Relevant answer
Answer
If you are just mounting the sample on one side to a TEM post and it's long ( say 25+ microns) and thinning down the entire protruding length below 100 nm then you will find that most materials will bend. There are a few reasons why this happens most have been mentioned already. Just mount it in the V of a omniprobe or similar grid attaching both ends. this will help considerably. If it still bends then when thinning don't mill the entire depth, leave a thicker bar running along the bottom for the full length. This will also work if mounted to a single post, even better to leave a bar up the side in the latter case as well.
  • asked a question related to FIB
Question
16 answers
Ideally I would like to know the thickness of both the barrier and the porous layer formed when aluminium is anodised.
One way I can think of is by taking a cross section of the anodised aluminium using a FIB and then examining under a TEM. This can be very time consuming however.
Does anyone have any other suggestions?
Relevant answer
Answer
you can try the PhotoElectron Spectroscopy in Air, which is commonly used to calculate and evaluate the thickness of contamination or passivated layers on metals.
The quantity of electrons emitted may be referred to the thickness of the layer you're investigating, the technique is really easy and handy and doesn't require a complex sample preparation
  • asked a question related to FIB
Question
3 answers
I want to make an Ag pattern of nano-disc on top of ITO. I know I can use DWL(EBL,FIB and TPP). I need to know the pros and cons of each of these relative to write time, economics and quality of nanostructures.
Relevant answer
Answer
Calum. Like I said in the main question, the nano-discs are 50 nm tall with a radii of about 100 nm with a period of 500 nm. Yes I want to pattern the whole area.  The nano-fabrication technique must be able to produce high resolution features.
I will take a look at the book you recommended. thanks
  • asked a question related to FIB
Question
7 answers
In slice and view applications of FIB/SEM dual beam systems, which software has a high quality 3D reconstructed volume image? 
Relevant answer
Answer
Sina,
It can also depend on your sample type.  Amira is good for biological samples while Avizo Fire is designed for materials research.  Simpleware is another tool that we use--it has more advanced capabilities in meshing 3D reconstructed data to use in modeling.
Julie
  • asked a question related to FIB
Question
11 answers
I want to see the damage created by laser using tight focusing inside sio2, for this I need to etch it or polish it up 5~10 micron. Can someone give suggestions on how to do this. FIB is one method but it is quite expensive. Is there any other inexpensive method?
Relevant answer
Answer
Just polishing by using small particle size diamond paper with the help of Gatan grinder can reach 10 um.
  • asked a question related to FIB
Question
6 answers
I'm interested in the 3D microstructure of a deformed Mg alloy. I would have access to a FIB and to a SEM with EBSD detector, which are two separate instruments.
Can anybody suggest a reliable procedure to realign the sample within both instruments avoiding misalignments (rotation and translation)? 
Can anyone suggest parameters for FIB preparation of Mg alloys?
Thanks.
Relevant answer
Answer
Commonly newer generations of FIBs have also a SEM (or better: the FIB is based on an SEM combined with a FIB-column). Therefore, nearly all investigations are done on a FIB attached with an EBSD system. Nevertheless, there are different configurations available which are used to switch between FIB mode and EBSD mode. In general one distinguishes between sample rotation around 180° and tilt, or only a sample tilt. Both have disadvantages since any movement willl cause problems in realignment of the sample after each step...and this for both, FIB preparation as well as EBSD acquistion. There are a few publications which discuss the specific advantages (but often not the disadvantages, or only the disadvantages of the complementary arrangment). TESCAN uses another approach which enables to prepare the surface and map it by EDS and/or EBSD without any sample tilt. The major problem there are is the curtaining since the resulting topography is then no more horizontally visible but it is slanted. How much this will disturb the results is not well discussed until now. At least I have not seen any publication about this topic.
In general, the interpretation of FIBed sample surfaces has specific problems. First is the very limited volume you can characterize. Second, the unknown or only estimated 3D coordinates of each orientation determination strongly limites any quantitative interpretation of data. Very critical is also the caused sample-beam interference. Since EBSD patterns display the interaction of the first few nanometres the definitely existing Ga implantation will affect your result so that a general statement might given only under specific assumptions.
  • asked a question related to FIB
Question
1 answer
Should I use composer stack or a visualizer Kai? is there any guide book for these softwares? I have some slice and view images and I want to do some reconstruction to obtain a 3-D image.
Relevant answer
Answer
I will be working with her soon!
As far as I know, you do not need extra software for 3D reconstruction. It is embedded and included!
  • asked a question related to FIB
Question
8 answers
I have Ni nano wire of ~200 nm diameter and 20 micron length. I am not able to get contact using EBL and lift off. FIB exposure damages nano wires, hence trying EBL. Deposition is not continuous, break near the nanowire, due to step. I hope I am able to explain.
Relevant answer
Answer
If you have access to an SEM with gas injection system, you could try to use FEBID to contact your nanowire (see attachment as an example).
Otherwise, I guess you need to give more details about how you place your NW on the contact pads, if there is any layer in between that may be insulating, etc... For instance it is very easy to deposit a carbon layer with your SEM, which can then hinter the contact between the NW and the electrodes.
Concerning the Au, even if it is grainy and you have shadow effects, as long as you deposit at least the same thickness as your NW, it should have been fine... Could it be that you Ni is oxidized? If I were you I would try an Ar plasma in situ to remove the Niox and then also use a few nm Ti as seed layer to improve the growth.
  • asked a question related to FIB
Question
15 answers
The attached file shows an EBSD image for a Ti strip with a thickness around 30 micrometers. The sample was prepared by fine mechanical polishing. The image quality is poor. How can I improve the image quality?
I have tried electropolishing, and I could not keep the sample edge well. In the next step, I will try FIB, but I don't know the parameters. Any suggestions? Thanks in advance.
Relevant answer
Answer
If you would like to use FIB milling, do not forget also to protect the top surface of your area of interest with Pt layer which you can deposit in situ FIB or a Dual Beam microscope using EBID/IBID (electron/ion-beam-induced deposition). In such a way you will protect the top surface of your sample from the harmful effect of Ga+ ions and you will also even out the top surface, which will minimise the curtaining artifact that can arise during milling. 
  • asked a question related to FIB
Question
5 answers
When I prepare the 3DAP sample of Mg alloy by FIB, the needle surface is not smooth. Is the rough surface due to the re-deposition. How could I improve the sample quality? BTW, I cleaned the sample by low voltage and low current, but it seems useless. Thanks.
Relevant answer
Answer
In that case, you have two possibilities. First is that high ion current is heating your sample and decomposing the alloy. Second one is that you are etching too fast and you have homoredeposition. I was making STM needles once and effect was the same, something on the surface. I have used low currents and lower energies, if I remember correctly. The last possibility is that you are implanting Ga ions into the sample and while heating gallium is going out.
  • asked a question related to FIB
Question
3 answers
I am looking for some extended information regarding the called "Theater Curtain" or "Waterfall" effect in FIB.
I checked in the book "Introduction to Focused Ion Beams: Instrumentation, Theory, Techniques and Practice" (by Lucille A. Gianuzzi and Fred A. Stevie), and in many articles ("Improvements in performance of focused ion beam cross-sectioning: aspects of ion–sample interaction", by Tohru Ishitani, Kaoru Umemura, Tsuyoshi Ohnishi, Toshie Yaguchi and Takeo Kamino was especially useful), but all the authors seem to describe it phenomenologically. I'm trying to get a deeper, more physical (basic) understanding of it, so I interpreted the descriptions and tried to figure out their meaning, but I'm not sure that my interpretation was fully correct.
If there is any expert in FIB milling or anyone who understands theater curtain effect well enough, just tell me what you think about it. Any help will be very appreciated.
For what I understood, the curtain effect is defined by the presence of striations in the milled cross-section, independently of their origin. Thus, if we classified it by the physical causes, there would be more than one kind of curtain effect, with different explanations for each one:
- A very typical case is when the topography of the samples is uneven due to an inefficient polishing or no polishing at all. We can take a rough surface as one with local "valleys" and regions with slope. In the valleys, the incidence angle will be ~90º and the sputtering yield will be maximum (the sputtering yield has a big dependence on the incidence angle), and in the regions with higher slope the sputtering yield will be very small.
If the beam is hitting a valley, the volume under the valley is milled. In this case, the beam tails won't have much importance since they will hit regions with a high slope and low sputtering rate (anything next to a valley has slope).
If the beam is hitting a region with a certain slope, the sputtered atoms will most likely go down that slope and cause a second order sputtering in the valley at the bottom of the slope, and the beam tails will do approximately the same. This way, the milled region will cover a larger area of the sample surface. I also think that it is quite possible that the ions themselves go down the slopes without the need of second order sputtering (something like ions not causing sputtering, but just rebounding with the slope surface) if the angle of incidence is small enough, but I am not really sure of that.
In any case, the combination of regions with valleys and varying slope will cause differences in the size of the milled regions of the sample, thus exhibiting the curtain effect.
- Another common case is when the composition of the milled material is not homogeneous, and consists in various components with different sputtering rates (due to different hardnesses, atomic numbers, etc.). As the sample moves (relatively to the beam) at a constant speed, the regions of its top surface (the one perpendicular to the beam) with lower sputtering rates get milled a smaller area than the regions with higher sputtering rates, which are more affected by the beam tails because milling is faster there.
If there wasn't anything else going on there, any changes in the composition under the top surface would also generate curtain effect (and kind of steps when the harder material is below), but to the extent I know, that doesn't happen. The explanation for that could be that because the tails affect mainly the parts closer to the top surface, instead of the cross-section being parallel to the beam, a slope is created in it (that actually is known to happen), so it covers a higher part of the top surface and more tails impact on it. The ions colliding against that inclined cross-section will generate sputtered atoms that will go down the slope, and cause second order sputtering if they hit an obstacle in their way, so that would sharpen the cross section in the direction (almost) parallel to the beam. That would explain why the changes in composition only have an effect in curtaining if they are in the top surface. Again, the possibility of ions going down the slope without causing sputtering in it would help that explanation a lot, since the sputtering yield against the cross-section is minimal due to the low angle of incidence. If ions from the tails rebounded against the cross section in a quite elastic way, they would go down it with almost the same kinetic energy than the others, and that would cause a higher concentration of ions than when the beam first impacts a region of the top surface. Due to this concentration of the beam, harder regions of the sample would be milled anyway.
- The third condition that can cause the theater curtain effect is the orientation of the sample, if it is crystalline, because ion channeling (ions penetrating greater distances across crystalline planes with lower Miller indices) results in preferential milling along low index directions. In this case I think that what simply happens is that, as planes with low Miller indices have greater distances among them, there is less linear density of atoms along their direction and more freedom for ions to travel across them (and the atoms of the sample are easier to move in those directions, too), so their impact on the material is greater.
I have seen other causes for curtain effect (the beam dose, bad aligning, the speed at which the sample is moved...), but I consider that they are circunstances that affect the three mentioned physical causes, but not causes by themselves.
That is what I was able to find out. Am I missing something? Is there something that I said that you don't agree with? Thank you very much in advance.
I'm sorry if it was messy to read. It was hard to explain it without any drawing.
Relevant answer
Answer
Nicholas, there is another excellent paper by Tohru Ishitani and Toshie Yaguchi: "Cross-Sectional Sample Preparation by Focused Ion Beam: A Review of Ion-Sample Interaction" published in Microscopy Research and Technique in 1996 which gives excellent overview of how X-sectional cut is produced by the FIB, and TEM sample preparation is nothing else but two cross-sections facing each other.
I think on qualitative (or as you put it "phenomenological") level you got everything right, including the forward-scattering of the sample material by primary ion beam. That is why deposition of thick layer of amorphous material above the X-section site reduces curtaining, same as in the case of silicone-on-top cross-sectioning of the semiconductor devices. Slowing down advancement of the vertical face of the cross-section, to allow sufficient time for removal of locations that happened to have lower spattering yield and thus protruding from the face of the X-section and "shadowing" underlying material, thus creating curtain-like appearance, eliminates this artifact for vast majority of practical purposes.
The waterfall effect is a different phenomenon then wavy surface near the edge of trench or ripples on the surface of diamond that are produced by FIB milling. I have not seen yet a paper that would look into details of the physics of formation of the front wall of the FIB cross-section and include mechanisms of the waterfall (curtaining) effect. Maybe you could write one at the end of your exploration of the subject ;)
On related note - I recall that a few years ago, either at ESREF or EFUG, was a presentation by a European group - if I am not mistaken it was EMPA, but I may be wrong here - on proposed model for FIB etching and software that allowed quite close modeling of FIB cross-sectioning. It could be that such model may be useful as a starting point for explaining physics of the curtaining.