Plasma Surface Engineering @ ALPS

modern microwave plasma generation

Solid State microwave generators open new directions in plasma generation with applications in industrial thin film processing. The optimization of the plasma production line, i.e. from the microwave generator to the plasma source, is a requisite to enable the scaling-up while ensuring a robust control.


The advantages of microwave plasma in the context of thin film deposition have been known for a long time. Industrial requirements for large scale plasma surface processing request plasma sources with increased performance in terms of control, density and uniformity over a wide area of operation. The recent development of solid state microwave generators and matched plasma sources allow to easily meet these industrial requirements.


To produce large volume plasmas an infinite number of elementary plasma sources could be arranged in bi- or tri-dimensional network. In this context the use of magnetron-based generators connected to power dividers does not allow for a good control of the microwave power distributed to each plasma source. To overcome these limitations microwave plasma sources have been designed to avoid power losses and to be used without any tuning system. Each source is connected to its own microwave solid state generator which produces a wave with variable frequency. This feature can be used to automatically compensate the low mismatching that may be created by changes in the operating conditions and in consequence to maintain the reflected power below 1 %.


Using the above described concepts of a simplified plasma production line, a PECVD reactor based on multiple plasma sources (Hi-Wave) has been designed. The system is currently applied to low temperature nanocrystalline diamond deposition and plasma nitriding of stainless steels.

Regular flow plasma systems such as surface wave launchers, e.g. Surfatron, Surfaguide, have been applied for plasma surface engineering to enhance the wettability of hard wood surfaces.




N2 Plasma: Hi-Wave 1600 W at 10 Pa

solid state MW generator 200W water cooled

O2 plasma : 8 Hi-Wave x 200 W at 10 Pa

Ar plasma: Aura Wave 160 W at 1 Pa

Ar plasma: Aura Wave 12 x 20 W at 0.1 Pa

Spectrum of solid state generator

Hi-WAVE elementary coaxial source


The new reactor system can be easily up-scaled without limitation by increasing the number of plasma sources and their distribution to allow for the treatment of large sample areas. The system is adapted to processes nanocrystalline diamond. In the case of the metal-organic precursors the reactor can be equally applied to metal oxide deposition with high aspect ratio.


The microwave equipment used by the Plasma Surface Engineering group has been purchased with internal BFH-TI funds and is currently dedicated to CTI Nano-Diamond and SATW Plassitec projects.

Hi-Wave at ICPIG 2015
Hi-Wave at ICPIP 2015
Hi-Wave at SVMT 2015 


 NeoCoat SA, La Chaux de Fonds, CH

Sairem SAS, France