The reason that these high deposition rates can be achieved is due to the fact that plasma production takes place in an upstream plasma source operated at sub-atmospheric pressure. At this high pressure, plasma production is very effective (with ionization degrees up to 10% and dissociation degrees up to 100% when molecular gases are used).
This results in large flows of reactive ions and/or neutrals once the plasma expands into a downstream, low-pressure region. In this region, the large ‘amount of reactivity’ can be used to dissociate large flows of deposition precursor gases (NH3, SiH4, H2, N2O, DEZ, TMA, etc.).
The remote nature of the ETP technique also allows for easier optimization of processing conditions and more freedom in reactor and substrate design and size. Finally, ion bombardment of the substrate is virtually absent as there is no electrical power coupling into the downstream plasma.
Using multiple ETP sources an excellent coating homogeneity is achieved. Typical coatings are SiNx, SiOx, amorphous Si and ZnO(Al) layers to be used as optical, protective or electrical coatings.
Applications are found in encapsulation of thin and flexible electronics and production of amorphous silicon coatings on anode foils for next generation Li-ion batteries.
Our proprietary expanding thermal plasma technology was developed in collaboration with the University of Technology in Eindhoven.