1. If you can - add something conductive to your epoxy used for embedding. Carbon nanoparticles, nanotubes, metal nanoparticles, etc... - anything that would help with bleeding away the charge.

2. Contrarily to popular belief, carbon tape is highly resistive! Check yourself - take small piece of carbon tape, ohmmeter, and see how much resistance you get in through-tape and along-the-tape direction. If you can - place your sample directly on SEM stub and use tiny amount of "High Conductivity Colloidal Silver" from Ted Pella (in my testing this is the most conductive silver paint on the market) to attach them. This paint is very liquid, so it would get under the sample by capillary force. If it does not - spread tiny amount of it on the stub and then place sample into it.

3. Since you are doing SEM, slightly thicker Ir coating (1nm - 2nm) would help with reducing charging while keeping degradation of resolution negligible.

4. If your SEM supports such imaging mode, use drift-corrected frame averaging with very fast scanning rates. If you are trying imaging with secondary electron signal try reducing electron beam current below 100pA.

5. Depending on capabilities of your SEM, reduce landing energy of primary electron beam down to 2KeV or even 1KeV if resolution is acceptable. Work with as low beam current at as short working distance as practical and use through-lens or through-beam detector (whatever it is called on the SEM you are using).

6. Try backscattered electron signal imaging with landing energies below 5KeV, landing energy around 2.5KeV would be a good point to start.

7. If SEM you are using has this capability work in "beam deceleration" or "retarding field" or "sample bias" mode.

8. Treat your samples with Ionic Liquid (IL-1000 from Hitachi or similar).

9. Mount your samples on a grid and use STEM imaging if the SEM you are using has such capability. If it does not - try STEM imaging with "STEM in SEM" holder; do not forget to properly orient it toward in-chamber SE detector.

10. Everything else failing - image samples by E-SEM in water atmosphere.

If you don't have any conductive resin, you can do;

1. You can use silver paste instead of carbon tape.

2. You can cover the edges of resim with silver paste and join with the carbon tape or silver paste.

3. Decrease the voltage and working distance.

Best regards,

Fatih.

The carbon tape uses presure sensitive adhesive; the resistance one finds with a simple multimeter is therefore of high value. In reality one need to press the tape as hard as possible onto the sample and stub failing which may cause high resistance and charging. In any case colloidal silver would be better choice than carbon tape.

Dear all,. 

Thanks for your suggestions .

I have used only silver paste to mount samples (embedded in a non-conductive resin) on the stubs and I coated them with Iridium 0.5 nm and 1 nm. I decided for 0.5 nm because I found the coating to be destructive on my samples.

The voltage I used is 2 kV and the current 0.40 nA, with a working distance of ~4 mm, a through the lens detector in backscattered electron acquisition modality.

Thanks to your suggestions, I was able to do imaging with stable images over several microns on volume analyzed.

Best, 

Paola