Cleaning is performed exclusively by reactive gas compounds which are formed by the chemical reaction of the plasma with carbonaceous material on the specimen and the specimen holder. The plasma is generated with a gas mixture of 25 % oxygen and 75 % argon. Free electrons are accelerated to a high velocitye by an oscillating electromagnetic field (13.56 MHz), exciting gas atoms and creating the plasma. The plasma ions strike the surface with energies of less than 12 eV, which is below the sputtering threshold of the sample.
The plasma cleaner can be used to remove organic contaminants from sample surfaces. At a pressure of about 1 mbar, oxygen gas is introduced into a process chamber and ionized by applying high frequency. The resulting plasma contains highly reactive oxygen radicals that are capable of oxidizing organic material even at low temperatures up to max. 180°C.
The ZONE-SEM removes thin hydrocarbon coatings from sample surfaces. The sample is exposed to short-wave UV radiation under vacuum, which breaks the hydrocarbon bonds and binds them with activated oxygen. Resulting H2O, CO and CO2 are removed by the vacuum system. The reduction of hydrocarbon layers on samples improves electron microscopic imaging by producing fewer contamination artifacts. This process can be used for all samples except hydrocarbon based materials as they will be damaged or etched by the process.
- Vacuum: 100 mbar
- Process time: 5 - 30 min