Remove Carbonaceous Hydrocarbon Contamination on TEM, SEM, FIB Samples and Chamber

PIE Scientific offers two plasma cleaning & surface activation solutions for TEM, SEM and FIB users

Tabletop plasma cleaner for TEM, SEM sample, and specimen holder cleaning

Tabletop Tergeo-EM plasma cleaner can accept two TEM specimen holders. It’s chamber is big enough for two 4″ wafers. Users can also insert TEM, SEM samples,s or grids directly into the plasma chamber.

TEM and SEM tabletop plasma cleaner
  • Removing hydrocarbon contamination on TEM and SEM samples before imaging.
  • Removing carbon deposition after STEM imaging.
  • Making TEM grid hydrophilic for cryo-EM applications. Unique gentle downstream mode and pulsed plasma can handle ultra-thin carbon and graphene grids without damaging the fragile grids
  • Removing organic contamination and activate in-situ TEM and SEM chip surface. Making liquid cell surface hydrophilic.
  • Support Thermo-fisher (FEI), JEOL and Hitachi specimen holder, cryo-em autoloader cassette, SEM stud, and regular TEM grids on any holders

Downstream in-situ plasma cleaner for sample and chamber cleaning on SEM, FIB, and TEM system

In-situ plasma cleaner for SEM, FIB and TEM system
In-situ plasma cleaner on FEI SEM and dual-beam FIB system
In-situ plasma cleaner on Zeiss Gemini SEM system
  • Removing hydrocarbon and fluorocarbon contamination on vacuum chamber wall
  • In-situ plasma clean SEM and FIB samples inside the vacuum, clean sample won’t be exposed to ambient air and get recontaminated.
  • Reduce pumping down time and improve vacuum

TEM specimen holder vacuum storage and leak check

TEM specimen holder and sample vacuum storage station
  • Keep specimen holder dry and clean, reduce the pump down time and reduce the contamination
  • Leak check the specimen holders

The importance of removing carbonaceous hydrocarbon contamination for SEM, FIB, and TEM samples and chambers

Carbonaceous hydrocarbon contamination can reduce image resolution and contrast

Lubricant oil, vacuum grease, high vapor pressure polymer and photoresist samples can introduce hydrocarbon contamination into SEM, FIB and TEM sample chamber. XPS data shows that surface of a clean sample will be contaminated by airborne hydrocarbon contamination after exposing to air for just one hour. For low-landing-energy high-resolution secondary-electron mode imaging on high-resolution FE-SEM, secondary electrons mostly come out of the thin top surface layer. If the sample surfaces are contaminated with a layer of hydrocarbon contaminations, signal electrons are mostly coming out of the contamination layers instead of the material of interest. Therefore, contamination can reduce image contrast and degrade image resolution.

SEM sample before and after plasma cleaning

Carbonaceous hydrocarbon contamination can impact X-ray material composition analysis

In X-ray analysis, high dose electron beam will irradiate the sample surface for a long time. If the sample chamber is heavily contaminated by hydrocarbon, carbon deposition will build up in the process. Carbon content will be higher than the actual percentage in the materials.

Carbonaceous hydrocarbon contamination can impact electron optics performance

Two components in electrons optics column are exposed to high dose of electron irradiation. Electron apertures are used to limit beam angle and control beam current by cutting off the high angle electrons. Aperture may also be used as beam blanker. SE detector is used to collect emitted secondary electron signals. These two components are not located in ultra-high vacuum section of the electron optics column. They are susceptible to heavily hydrocarbon contamination build-up if the sample chamber is not clean. Hydrocarbon is not a good conductor. It can create unstable charging issue inside the electron optics column. Therefore, focus and beam position may drift during long slow scan because electrostatic charge will accumulate on the hydrocarbon layer. Localized charging inside the electron optics column can also increase electron optics aberrations and reduce electron optics resolution.

Principle of in-situ sample and chamber cleaning using downstream plasma cleaners

Remote plasma source (EM-KLEEN or SEMI-KLEEN) can be attached to the SEM and FIB chamber. Once user closes electron gun gate valve and turns off high voltages. The gas dosing valve inside the plasma cleaner will start introduce process gas (usually air) into the plasma cleaner at very low flow rate (less than 30sccm). Rf energy will ionize the oxygen or hydrogen gas and generate atomic oxygen, atomic hydrogen and OH. Those reactive radicals will then diffuse into the SEM or FIB chamber and react with the hydrocarbon contaminations on the sample and inside the chamber. The byproducts are usually low vapor pressure gas species that can be easily pumped away by vacuum pump. Remote plasma cleaner can clean sample and chamber at the same time.

Principle of in-situ plasma cleaning for SEM, FIB and TEM system
Principle of downstream plasma cleaning for SEM, FIB, TEM and other high vacuum systems

Off-line carbonaceous hydrocarbon contamination cleaning for SEM and TEM samples

SEM and TEM samples can be pre-cleaned using Tergeo-EM tabletop plasma cleaners. If air, Ar+O2 or H2 gases are used to generate plasma in Tergeo-EM plasma cleaner, radicals can effectively remove the hydrocarbon contaminations on the sample surface. Tergeo-EM plasma cleaner is the only TEM/SEM plasma cleaner that has integrated both immersion mode plasma cleaning (samples are immersed in plasma) and downstream mode plasma cleaning (samples are placed outside the plasma) in one system. Downstream plasma clean can be used to clean delicate samples that contains carbon, such as graphene, DLC (diamond-like carbon), carbon nanotube or for samples with very thin coatings. In addition, unique pulsed mode operation can generate extremely short plasma pulses to further reduced the plasma intensity for delicate samples. Patented plasma sensor technology monitors the plasma strength in real-time. It helps users to set up the right cleaning recipe for different types of samples.